Kilukkam (1991)

This offbeat romantic comedy revolves around Nandini (Revathy), a tourist who comes to Ooty and finds Joji (Mohanlal), a tourist guide down on his luck. Joji initially believes that Nandini is an extremely wealthy heiress, and hangs around her in the hopes that she would be the answer to his financial crisis. However, it turns out that Nandini has mental retardation, and a series of events make her presence in Ooty intertwined with the lives of Joji and his friend Nischal (Jagathy Sreekumar). As Nandini begins to live with them, hilarity ensues in their misguided attempts in getting of her. However, they find out that she is an escaped mental patient who has a bounty on her safe return. When they find that the bounty has been increasing for a while, they decide to hide her for a while and claim the bounty when it gets big enough. In time, they realize that things are not as they seem, and more complications are unraveled. What is the secret Nandini is hiding behind her child-like mask?