Thoonga Vanam starring Kamal Haasan and Trisha in the lead roles is touted to be a thriller film that takes place overnight. Kamal Haasan has played the role of a cop. He gets hold of a drug courier and finds cocaine hidden in it. Prakash Raj, a drug smuggler kidnaps Kamal’s son and demands Kamal for the cocaine. How Kamal saves his son form the crux of the story.