diff --git a/LEGO1/lego/legoomni/include/registrationbook.h b/LEGO1/lego/legoomni/include/registrationbook.h
index c941ce5c..5ff61bdd 100644
--- a/LEGO1/lego/legoomni/include/registrationbook.h
+++ b/LEGO1/lego/legoomni/include/registrationbook.h
@@ -68,6 +68,7 @@ class RegistrationBook : public LegoWorld {
 	MxLong HandleKeyPress(MxS8 p_key);
 	MxLong HandleClick(LegoControlManagerEvent& p_param);
 	MxLong HandleNotification19(MxParam& p_param);
+	void FUN_100775c(MxS16 p_playerIndex);
 };
 
 #endif // REGISTRATIONBOOK_H
diff --git a/LEGO1/lego/legoomni/src/worlds/registrationbook.cpp b/LEGO1/lego/legoomni/src/worlds/registrationbook.cpp
index 3775b1bc..b7e510cf 100644
--- a/LEGO1/lego/legoomni/src/worlds/registrationbook.cpp
+++ b/LEGO1/lego/legoomni/src/worlds/registrationbook.cpp
@@ -12,6 +12,7 @@
 #include "mxmisc.h"
 #include "mxnotificationmanager.h"
 #include "mxtimer.h"
+#include "mxtransitionmanager.h"
 #include "regbook_actions.h"
 
 DECOMP_SIZE_ASSERT(RegistrationBook, 0x2d0)
@@ -113,10 +114,49 @@ MxLong RegistrationBook::HandleKeyPress(MxS8 p_key)
 	return 0;
 }
 
-// STUB: LEGO1 0x100774a0
+// FUNCTION: LEGO1 0x100774a0
 MxLong RegistrationBook::HandleClick(LegoControlManagerEvent& p_param)
 {
-	return 0;
+	MxS16 l = p_param.GetUnknown0x28();
+	if (1 <= l && 28 >= l) {
+		if (p_param.GetClickedObjectId() == RegbookScript::c_Alphabet_Ctl) {
+			if (l == 28) {
+				DeleteObjects(&m_atom, RegbookScript::c_iic006in_RunAnim, RegbookScript::c_iic008in_PlayWav);
+				if (GameState()->GetCurrentAct() == 0) {
+					m_infocenterState->SetUnknown0x74(15);
+				}
+				else {
+					m_infocenterState->SetUnknown0x74(2);
+				}
+
+				TransitionManager()->StartTransition(MxTransitionManager::e_mosaic, 50, FALSE, FALSE);
+			}
+			else {
+				if (28 < l) {
+					return 1;
+				}
+
+				HandleKeyPress(l < 27 ? l + 0x40 : 8);
+			}
+		}
+		else {
+			InputManager()->DisableInputProcessing();
+			DeleteObjects(&m_atom, RegbookScript::c_iic006in_RunAnim, RegbookScript::c_iic008in_PlayWav);
+			MxS16 i;
+			for (i = 0; i < 10; i++) {
+				if (m_checkmark[i]->GetAction()->GetObjectId() == p_param.GetClickedObjectId()) {
+					break;
+				}
+			}
+			FUN_100775c(i);
+		}
+	}
+	return 1;
+}
+
+// STUB: LEGO1 0x100775c0
+void RegistrationBook::FUN_100775c(MxS16 p_playerIndex)
+{
 }
 
 // FUNCTION: LEGO1 0x10077cc0