diff --git a/src/sequence_diagram/generators/plantuml/sequence_diagram_generator.cc b/src/sequence_diagram/generators/plantuml/sequence_diagram_generator.cc
index 2c3a6b79..a425c010 100644
--- a/src/sequence_diagram/generators/plantuml/sequence_diagram_generator.cc
+++ b/src/sequence_diagram/generators/plantuml/sequence_diagram_generator.cc
@@ -78,10 +78,10 @@ void generator::generate_return(const message &m, std::ostream &ostr) const
 }
 
 void generator::generate_activity(const activity &a, std::ostream &ostr,
-    std::set<common::model::diagram_element::id_t> &visited) const
+    std::vector<common::model::diagram_element::id_t> &visited) const
 {
     for (const auto &m : a.messages) {
-        visited.emplace(m.from);
+        visited.push_back(m.from);
 
         const auto &to = m_model.get_participant<model::participant>(m.to);
         if (!to)
@@ -94,12 +94,16 @@ void generator::generate_activity(const activity &a, std::ostream &ostr,
         ostr << "activate " << to.value().alias() << std::endl;
 
         if (m_model.sequences.find(m.to) != m_model.sequences.end()) {
-            if (visited.find(m.to) ==
+            if (std::find(visited.begin(), visited.end(), m.to) ==
                 visited.end()) { // break infinite recursion on recursive calls
                 LOG_DBG("Creating activity {} --> {} - missing sequence {}",
                     m.from, m.to, m.to);
                 generate_activity(m_model.sequences[m.to], ostr, visited);
             }
+//            else {
+//                // clear the visited list after breaking the loop
+//                visited.clear();
+//            }
         }
         else
             LOG_DBG("Skipping activity {} --> {} - missing sequence {}", m.from,
@@ -107,6 +111,8 @@ void generator::generate_activity(const activity &a, std::ostream &ostr,
 
         generate_return(m, ostr);
 
+        visited.pop_back();
+
         ostr << "deactivate " << to.value().alias() << std::endl;
     }
 }
@@ -182,9 +188,18 @@ void generator::generate(std::ostream &ostr) const
                     break;
                 }
             }
-            std::set<common::model::diagram_element::id_t> visited_participants;
+            std::vector<common::model::diagram_element::id_t> visited_participants;
+
+            const auto& from = m_model.get_participant<model::participant>(start_from);
+
+            generate_participant(ostr, start_from);
+
+            ostr << "activate " << from.value().alias() << std::endl;
+
             generate_activity(
                 m_model.sequences[start_from], ostr, visited_participants);
+
+            ostr << "deactivate " << from.value().alias() << std::endl;
         }
         else {
             // TODO: Add support for other sequence start location types
diff --git a/src/sequence_diagram/generators/plantuml/sequence_diagram_generator.h b/src/sequence_diagram/generators/plantuml/sequence_diagram_generator.h
index fc3c82b9..e2148bee 100644
--- a/src/sequence_diagram/generators/plantuml/sequence_diagram_generator.h
+++ b/src/sequence_diagram/generators/plantuml/sequence_diagram_generator.h
@@ -56,7 +56,7 @@ public:
 
     void generate_activity(const clanguml::sequence_diagram::model::activity &a,
         std::ostream &ostr,
-        std::set<common::model::diagram_element::id_t> &visited) const;
+        std::vector<common::model::diagram_element::id_t> &visited) const;
 
     void generate(std::ostream &ostr) const;
 
diff --git a/src/sequence_diagram/model/participant.h b/src/sequence_diagram/model/participant.h
index 2720bef5..d2abc452 100644
--- a/src/sequence_diagram/model/participant.h
+++ b/src/sequence_diagram/model/participant.h
@@ -115,11 +115,16 @@ public:
 
     void is_alias(bool alias) { is_alias_ = alias; }
 
+    bool is_lambda() const { return is_lambda_; }
+
+    void is_lambda(bool is_lambda) { is_lambda_ = is_lambda; }
+
 private:
     bool is_struct_{false};
     bool is_template_{false};
     bool is_template_instantiation_{false};
     bool is_alias_{false};
+    bool is_lambda_{false};
 
     std::map<std::string, clanguml::class_diagram::model::type_alias>
         type_aliases_;
@@ -127,6 +132,12 @@ private:
     std::string full_name_;
 };
 
+struct lambda : public class_ {
+    using class_::class_;
+
+    std::string type_name() const override { return "lambda"; }
+};
+
 struct function : public participant {
     function(const common::model::namespace_ &using_namespace);
 
diff --git a/src/sequence_diagram/visitor/translation_unit_visitor.cc b/src/sequence_diagram/visitor/translation_unit_visitor.cc
index b0bb88d3..409b84fd 100644
--- a/src/sequence_diagram/visitor/translation_unit_visitor.cc
+++ b/src/sequence_diagram/visitor/translation_unit_visitor.cc
@@ -99,6 +99,9 @@ bool translation_unit_visitor::VisitCXXRecordDecl(clang::CXXRecordDecl *cls)
     if (cls->isLocalClass())
         return true;
 
+    LOG_DBG("Visiting class declaration at {}",
+        cls->getBeginLoc().printToString(source_manager()));
+
     // Build the class declaration and store it in the diagram, even
     // if we don't need it for any of the participants of this diagram
     auto c_ptr = create_class_declaration(cls);
@@ -400,6 +403,73 @@ bool translation_unit_visitor::VisitFunctionTemplateDecl(
     return true;
 }
 
+bool translation_unit_visitor::VisitLambdaExpr(clang::LambdaExpr *expr)
+{
+    const auto lambda_full_name =
+        expr->getLambdaClass()->getCanonicalDecl()->getNameAsString();
+
+    LOG_DBG("Visiting lambda expression {} at {}", lambda_full_name,
+        expr->getBeginLoc().printToString(source_manager()));
+
+    LOG_DBG("Lambda call operator ID {} - lambda class ID {}, class call "
+            "operator ID {}",
+        expr->getCallOperator()->getID(), expr->getLambdaClass()->getID(),
+        expr->getLambdaClass()->getLambdaCallOperator()->getID());
+
+    // Create lambda class participant
+    auto *cls = expr->getLambdaClass();
+    auto c_ptr = create_class_declaration(cls);
+
+    if (!c_ptr)
+        return true;
+
+    const auto cls_id = c_ptr->id();
+
+    set_unique_id(cls->getID(), cls_id);
+
+    // Create lambda class operator() participant
+    auto m_ptr = std::make_unique<sequence_diagram::model::method>(
+        config().using_namespace());
+
+    common::model::namespace_ ns{c_ptr->get_namespace()};
+    auto method_name = "operator()";
+    m_ptr->set_method_name(method_name);
+    ns.pop_back();
+
+    m_ptr->set_class_id(cls_id);
+    m_ptr->set_class_full_name(c_ptr->full_name(false));
+
+    diagram().add_participant(std::move(c_ptr));
+
+    m_ptr->set_id(common::to_id(
+        get_participant(cls_id).value().full_name(false) + "::" + method_name));
+
+    context().enter_lambda_expression(m_ptr->id());
+
+    set_unique_id(expr->getCallOperator()->getID(), m_ptr->id());
+
+    diagram().add_participant(std::move(m_ptr));
+
+    [[maybe_unused]] const auto is_generic_lambda = expr->isGenericLambda();
+
+    return true;
+}
+
+bool translation_unit_visitor::TraverseLambdaExpr(clang::LambdaExpr *expr)
+{
+    const auto lambda_full_name =
+        expr->getLambdaClass()->getCanonicalDecl()->getNameAsString();
+
+    RecursiveASTVisitor<translation_unit_visitor>::TraverseLambdaExpr(expr);
+
+    LOG_DBG("Leaving lambda expression {} at {}", lambda_full_name,
+        expr->getBeginLoc().printToString(source_manager()));
+
+    context().leave_lambda_expression();
+
+    return true;
+}
+
 bool translation_unit_visitor::VisitCallExpr(clang::CallExpr *expr)
 {
     using clanguml::common::model::message_t;
@@ -424,6 +494,10 @@ bool translation_unit_visitor::VisitCallExpr(clang::CallExpr *expr)
     m.type = message_t::kCall;
     m.from = context().caller_id();
 
+    if (context().lambda_caller_id() != 0) {
+        m.from = context().lambda_caller_id();
+    }
+
     const auto &current_ast_context = *context().get_ast_context();
 
     LOG_DBG("Visiting call expression at {}",
@@ -433,6 +507,26 @@ bool translation_unit_visitor::VisitCallExpr(clang::CallExpr *expr)
             clang::dyn_cast_or_null<clang::CXXOperatorCallExpr>(expr);
         operator_call_expr != nullptr) {
         // TODO: Handle C++ operator calls
+
+        LOG_DBG("Operator call expression to {} at {}",
+            expr->getCalleeDecl()->getID(),
+            expr->getBeginLoc().printToString(source_manager()));
+
+        auto maybe_id = get_unique_id(expr->getCalleeDecl()->getID());
+        if (maybe_id.has_value()) {
+            // Found operator() call to a participant
+            // auto maybe_participant = get_participant(maybe_id.value());
+            // if (maybe_participant.has_value()) {
+            m.to = maybe_id.value();
+            m.message_name = "operator()";
+            //}
+        }
+        else {
+            m.to = expr->getCalleeDecl()->getID();
+            m.message_name = "operator()";
+        }
+
+        if (clang::dyn_cast<clang::ImplicitCastExpr>(expr)) { }
     }
     //
     // Call to a class method
@@ -637,6 +731,9 @@ bool translation_unit_visitor::VisitCallExpr(clang::CallExpr *expr)
                             auto *ftd = clang::dyn_cast_or_null<
                                 clang::FunctionTemplateDecl>(decl);
 
+                            if (!get_unique_id(ftd->getID()).has_value())
+                                continue;
+
                             m.to = get_unique_id(ftd->getID()).value();
                             auto message_name =
                                 diagram()
@@ -751,11 +848,16 @@ translation_unit_visitor::create_class_declaration(clang::CXXRecordDecl *cls)
     auto qualified_name =
         cls->getQualifiedNameAsString(); //  common::get_qualified_name(*cls);
 
-    if (!diagram().should_include(qualified_name))
-        return {};
+    if (!cls->isLambda())
+        if (!diagram().should_include(qualified_name))
+            return {};
 
     auto ns = common::get_tag_namespace(*cls);
 
+    if (cls->isLambda() &&
+        !diagram().should_include(ns.to_string() + "::lambda"))
+        return {};
+
     const auto *parent = cls->getParent();
 
     if (parent && parent->isRecord()) {
@@ -815,6 +917,23 @@ translation_unit_visitor::create_class_declaration(clang::CXXRecordDecl *cls)
 
         c.nested(true);
     }
+    else if (cls->isLambda()) {
+        c.is_lambda(true);
+        if (cls->getParent()) {
+            auto parent_full_name = get_participant(context().caller_id())
+                                        .value()
+                                        .full_name_no_ns();
+
+            const auto location = cls->getLocation();
+            const auto type_name =
+                fmt::format("{}##(lambda {}:{})", parent_full_name,
+                    source_manager().getSpellingLineNumber(location),
+                    source_manager().getSpellingColumnNumber(location));
+            c.set_name(type_name);
+            c.set_namespace(ns);
+            c.set_id(common::to_id(c.full_name(false)));
+        }
+    }
     else {
         c.set_name(common::get_tag_name(*cls));
         c.set_namespace(ns);
@@ -1208,6 +1327,35 @@ void translation_unit_visitor::process_template_specialization_argument(
             simplify_system_template(argument,
                 argument.to_string(config().using_namespace(), false));
         }
+        else if (arg.getAsType()->getAsCXXRecordDecl()) {
+            if (arg.getAsType()->getAsCXXRecordDecl()->isLambda()) {
+                if (get_unique_id(
+                        arg.getAsType()->getAsCXXRecordDecl()->getID())
+                        .has_value()) {
+                    argument.set_name(get_participant(
+                        get_unique_id(
+                            arg.getAsType()->getAsCXXRecordDecl()->getID())
+                            .value())
+                                          .value()
+                                          .full_name(false));
+                }
+                else {
+                    auto parent_full_name =
+                        get_participant(context().caller_id())
+                            .value()
+                            .full_name_no_ns();
+
+                    const auto location =
+                        arg.getAsType()->getAsCXXRecordDecl()->getLocation();
+                    const auto type_name =
+                        fmt::format("{}##(lambda {}:{})", parent_full_name,
+                            source_manager().getSpellingLineNumber(location),
+                            source_manager().getSpellingColumnNumber(location));
+
+                    argument.set_name(type_name);
+                }
+            }
+        }
         else if (arg.getAsType()->getAs<clang::TemplateTypeParmType>()) {
             auto type_name =
                 common::to_string(arg.getAsType(), cls->getASTContext());
@@ -1312,6 +1460,41 @@ void translation_unit_visitor::process_template_specialization_argument(
 
         cls->getLocation().dump(source_manager());
     }
+    //    else if (arg.getKind() == clang::TemplateArgument::Expression) {
+    //        if (clang::dyn_cast<clang::LambdaExpr>(arg.getAsExpr()) !=
+    //        nullptr) {
+    //            class_diagram::model::template_parameter argument;
+    ////            const auto location =
+    ////                arg.getAsType()->getAsCXXRecordDecl()->getLocation();
+    ////
+    ////            auto type_name = fmt::format("(lambda {}:{}:{})",
+    ////                source_manager().getFilename(location).str(),
+    ////                source_manager().getSpellingLineNumber(location),
+    ////                source_manager().getSpellingColumnNumber(location));
+    ////
+    ////            argument.set_name(type_name);
+    //
+    //            if (get_unique_id(
+    //                    arg.getAsType()->getAsCXXRecordDecl()->getID())
+    //                    .has_value()) {
+    //                argument.set_name(get_participant(
+    //                    get_unique_id(
+    //                        arg.getAsType()->getAsCXXRecordDecl()->getID())
+    //                        .value())
+    //                                      .value()
+    //                                      .full_name(false));
+    //            }
+    //            else {
+    //                const auto location =
+    //                    arg.getAsType()->getAsCXXRecordDecl()->getLocation();
+    //                auto type_name = fmt::format("(lambda {}:{}:{})",
+    //                    source_manager().getFilename(location).str(),
+    //                    source_manager().getSpellingLineNumber(location),
+    //                    source_manager().getSpellingColumnNumber(location));
+    //                argument.set_name(type_name);
+    //            }
+    //        }
+    //    }
     else if (argument_kind == clang::TemplateArgument::Pack) {
         // This will only work for now if pack is at the end
         size_t argument_pack_index{argument_index};
@@ -1534,4 +1717,15 @@ bool translation_unit_visitor::simplify_system_template(
     else
         return false;
 }
+
+void translation_unit_visitor::finalize()
+{
+    for (auto &[id, activity] : diagram().sequences) {
+        for (auto &m : activity.messages) {
+            if (local_ast_id_map_.find(m.to) != local_ast_id_map_.end()) {
+                m.to = local_ast_id_map_.at(m.to);
+            }
+        }
+    }
+}
 }
diff --git a/src/sequence_diagram/visitor/translation_unit_visitor.h b/src/sequence_diagram/visitor/translation_unit_visitor.h
index 02d42516..a5223121 100644
--- a/src/sequence_diagram/visitor/translation_unit_visitor.h
+++ b/src/sequence_diagram/visitor/translation_unit_visitor.h
@@ -25,6 +25,8 @@
 #include <clang/AST/RecursiveASTVisitor.h>
 #include <clang/Basic/SourceManager.h>
 
+#include <stack>
+
 namespace clanguml::sequence_diagram::visitor {
 
 std::string to_string(const clang::FunctionTemplateDecl *decl);
@@ -150,12 +152,39 @@ struct call_expression_context {
 
     std::int64_t caller_id() const { return current_caller_id_; }
 
+    std::int64_t lambda_caller_id() const
+    {
+        if(current_lambda_caller_id_.empty())
+            return 0;
+
+        return current_lambda_caller_id_.top();
+    }
+
     void set_caller_id(std::int64_t id)
     {
         LOG_DBG("Setting current caller id to {}", id);
         current_caller_id_ = id;
     }
 
+    void enter_lambda_expression(std::int64_t id)
+    {
+        LOG_DBG("Setting current lambda caller id to {}", id);
+
+        assert(id != 0);
+
+        current_lambda_caller_id_.push(id);
+    }
+
+    void leave_lambda_expression()
+    {
+        assert(!current_lambda_caller_id_.empty());
+
+        LOG_DBG("Leaving current lambda expression id to {}",
+            current_lambda_caller_id_.top());
+
+        current_lambda_caller_id_.pop();
+    }
+
     clang::CXXRecordDecl *current_class_decl_;
     clang::ClassTemplateDecl *current_class_template_decl_;
     clang::ClassTemplateSpecializationDecl
@@ -166,6 +195,7 @@ struct call_expression_context {
 
 private:
     std::int64_t current_caller_id_;
+    std::stack<std::int64_t> current_lambda_caller_id_;
 };
 
 class translation_unit_visitor
@@ -180,6 +210,10 @@ public:
 
     virtual bool VisitCallExpr(clang::CallExpr *expr);
 
+    virtual bool VisitLambdaExpr(clang::LambdaExpr *expr);
+
+    virtual bool TraverseLambdaExpr(clang::LambdaExpr *expr);
+
     virtual bool VisitCXXMethodDecl(clang::CXXMethodDecl *method);
 
     virtual bool VisitCXXRecordDecl(clang::CXXRecordDecl *cls);
@@ -200,7 +234,7 @@ public:
 
     call_expression_context &context();
 
-    void finalize() { }
+    void finalize();
 
     template <typename T = model::participant>
     common::optional_ref<T> get_participant(const clang::Decl *decl)
diff --git a/tests/t20012/.clang-uml b/tests/t20012/.clang-uml
new file mode 100644
index 00000000..bd288238
--- /dev/null
+++ b/tests/t20012/.clang-uml
@@ -0,0 +1,14 @@
+compilation_database_dir: ..
+output_directory: puml
+diagrams:
+  t20012_sequence:
+    type: sequence
+    glob:
+      - ../../tests/t20012/t20012.cc
+    include:
+      namespaces:
+        - clanguml::t20012
+    using_namespace:
+      - clanguml::t20012
+    start_from:
+      - function: "clanguml::t20012::tmain()"
\ No newline at end of file
diff --git a/tests/t20012/t20012.cc b/tests/t20012/t20012.cc
new file mode 100644
index 00000000..488211a3
--- /dev/null
+++ b/tests/t20012/t20012.cc
@@ -0,0 +1,73 @@
+#include <functional>
+#include <utility>
+
+namespace clanguml {
+namespace t20012 {
+struct A {
+    void a() { aa(); }
+
+    void aa() { aaa(); }
+
+    void aaa() { }
+};
+
+struct B {
+    void b() { bb(); }
+
+    void bb() { bbb(); }
+
+    void bbb() { }
+};
+
+struct C {
+    void c() { cc(); }
+
+    void cc() { ccc(); }
+
+    void ccc() { }
+};
+
+template <typename F> struct R {
+    R(F &&f)
+        : f_{std::move(f)}
+    {
+    }
+
+    void r() { f_(); }
+
+    F f_;
+};
+
+void tmain()
+{
+    A a;
+    B b;
+    C c;
+
+    // The activity shouldn't be marked at the lambda definition, but
+    // wherever it is actually called...
+    auto alambda = [&a, &b]() {
+        a.a();
+        b.b();
+    };
+
+    // ...like here
+    alambda();
+
+    // There should be no call to B in the sequence diagram as the blambda
+    // is never called
+    [[maybe_unused]] auto blambda = [&b]() { b.b(); };
+
+    // Nested lambdas should also work
+    auto clambda = [alambda, &c]() {
+        c.c();
+        alambda();
+    };
+    clambda();
+
+    R r{[&c]() { c.c(); }};
+
+    r.r();
+}
+}
+}
\ No newline at end of file
diff --git a/tests/t20012/test_case.h b/tests/t20012/test_case.h
new file mode 100644
index 00000000..16681581
--- /dev/null
+++ b/tests/t20012/test_case.h
@@ -0,0 +1,66 @@
+/**
+ * tests/t20012/test_case.h
+ *
+ * Copyright (c) 2021-2022 Bartek Kryza <bkryza@gmail.com>
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+TEST_CASE("t20012", "[test-case][sequence]")
+{
+    auto [config, db] = load_config("t20012");
+
+    auto diagram = config.diagrams["t20012_sequence"];
+
+    REQUIRE(diagram->name == "t20012_sequence");
+
+    auto model = generate_sequence_diagram(*db, diagram);
+
+    REQUIRE(model->name() == "t20012_sequence");
+
+    auto puml = generate_sequence_puml(diagram, *model);
+    AliasMatcher _A(puml);
+
+    REQUIRE_THAT(puml, StartsWith("@startuml"));
+    REQUIRE_THAT(puml, EndsWith("@enduml\n"));
+
+    // Check if all calls exist
+    REQUIRE_THAT(puml,
+        HasCall(_A("tmain()"), _A("tmain()##(lambda 49:20)"), "operator()"));
+    REQUIRE_THAT(puml, HasCall(_A("tmain()##(lambda 49:20)"), _A("A"), "a"));
+    REQUIRE_THAT(puml, HasCall(_A("A"), _A("A"), "aa"));
+    REQUIRE_THAT(puml, HasCall(_A("A"), _A("A"), "aaa"));
+
+    REQUIRE_THAT(puml, HasCall(_A("tmain()##(lambda 49:20)"), _A("B"), "b"));
+    REQUIRE_THAT(puml, HasCall(_A("B"), _A("B"), "bb"));
+    REQUIRE_THAT(puml, HasCall(_A("B"), _A("B"), "bbb"));
+
+    REQUIRE_THAT(puml, HasCall(_A("tmain()##(lambda 62:20)"), _A("C"), "c"));
+    REQUIRE_THAT(puml, HasCall(_A("C"), _A("C"), "cc"));
+    REQUIRE_THAT(puml, HasCall(_A("C"), _A("C"), "ccc"));
+    REQUIRE_THAT(puml,
+        HasCall(_A("tmain()##(lambda 62:20)"), _A("tmain()##(lambda 49:20)"),
+            "operator()"));
+
+    REQUIRE_THAT(puml, HasCall(_A("C"), _A("C"), "ccc"));
+
+    REQUIRE_THAT(puml, HasCall(_A("tmain()"), _A("R<R##(lambda 68:9)>"), "r"));
+    REQUIRE_THAT(puml,
+        HasCall(_A("R<R##(lambda 68:9)>"), _A("tmain()##(lambda 68:9)"),
+            "operator()"));
+    REQUIRE_THAT(
+        puml, HasCall(_A("tmain()##(lambda 68:9)"), _A("C"), "c"));
+
+    save_puml(
+        "./" + config.output_directory() + "/" + diagram->name + ".puml", puml);
+}
\ No newline at end of file
diff --git a/tests/test_cases.cc b/tests/test_cases.cc
index 287a9539..af89443c 100644
--- a/tests/test_cases.cc
+++ b/tests/test_cases.cc
@@ -258,6 +258,7 @@ using namespace clanguml::test::matchers;
 #include "t20009/test_case.h"
 #include "t20010/test_case.h"
 #include "t20011/test_case.h"
+#include "t20012/test_case.h"
 
 ///
 /// Package diagram tests