Plot: Thittam Irandu begins with what could be a familiar mix-up to many of us. A woman boards a sleeper bus only to discover that she has to share her berth with a man! The woman is Aadhira, a police inspector. The man, Arjun (Subash Selvam), seems to be a gentleman, and Aadhira is taken in by his actions, and even develops a crush on him.