Vetri (Ashok Selvan) is a newly graduated criminology student who has an immense passion in becoming a detective. He has a very good observing capacity, which makes his professor Govardhan (Rajan Iyer) believe that he will become a good detective someday. He gets a job from a detective company where his bosses Sadagopan (Pradeep Nair) and Sailesh (Jayakumar) assign him with tasks of shadowing and surveillance. He stays with his best friend Nambi (Kaali Venkat) and collects all the details about his targets. His next target is Madhu (Janani Iyer), a beautiful girl, for whom Vetri falls at first sight.
Vetri soon realises that his completed targets are killed one by one, that someone has used him to collect details about the victims, and that the next one on the list is Madhu. He teams up with police inspector Raghuram (Jayaprakash) to investigate the murders. On thorough investigation, Vetri finds that his bosses Sailesh and Sadagopan are the culprits. Sadagopan works at an insurance company, and takes insurance policies for people who are single. The first two installments are paid, but by the third installment, the policy holders die in an "accident" provoked by Sailesh. The policies are then claimed by another unknown person having a fake relationship with the policy holder. The third person is then found to be called Vallabha. Vetri and Raghuram trace out the claimant of a policy, who turns out to be none other than professor Govardhan, who motivated Vetri to become a detective. Confronted by Vetri, the professor confesses before he commits suicide.
It is then shown that Vetri lives happily with friends and family taking care of the professor's old mother. Things turn fishy however, when a newspaper containing a visiting card of Vallabha is delivered to Vetri, asking him to "pick up the call". Vetri realises that even though his professor was involved in the insurance scam, he wasn't Vallabha and that the actual Vallabha is still at large. The story ends with Vetri picking up an incoming call.
