Best friends Vani "Vasu" Subramaniam [Jyothika] and Radhika Menon are carefree pranksters at a prestigious ladies' college in Chennai. They stay up late, break rules, and wreak havoc at their hostel, much to their lecturers' annoyance. They also form a rivalry against Geetha, the college queen bee. Malathi [Lakshmi], Radhika's aunt, wants her niece to complete her studies so that she can take over her late parents' multi-million business. To steer Radhika away from marriage, Malathi arranges for her to get married, setting a path that will ripple through everything that follows.
At this point, Vasu and Radhika are introduced to Gayathri [Tabu], a fiercely independent and capable police officer who is also an alumna of their college. During a college event, Gayathri explains how women in the country often lose their independence and livelihood after getting married. This moment plants a seed in the girls: they should resist marriage as long as possible. To avoid Malathi’s matchmaking schemes, Vani and Radhika pretend that Radhika has a boyfriend from overseas, a man named Ramesh, weaving an elaborate fantasy to keep prying relatives at bay. The pretend romance buys them time, but trouble arrives when a real person named Ramesh contacts them, claiming to be the very boyfriend they invented. To end this nuisance, Vasu and Radhika invite Ramesh to their hostel during a college dance program and plan to coax him into revealing the truth. Vasu even instructs Radhika to bring her aunt’s guns for their safety, turning a prank into a dangerous ruse.
The plan is derailed when a mysterious shooter kills Ramesh before the girls can confront him. With fear of being fingered as accomplices, they decide to dispose of the body by hiding it in an air ventilator. The body unexpectedly slides down the vent and lands on the auditorium stage in the middle of a performance, just as Gayathri, the guest of honour, oversees the event. She finds Radhika’s necklace on the body, and the two girls are suddenly hauled in for questioning. A twist deepens when an old woman shows up at the police station, claiming that Ramesh is her son who has gone missing. Seeing the noose tighten and realizing their innocence may not be believed, Vasu and Radhika escape custody and hide in an abandoned mansion on the city’s outskirts.
Now the prime suspects, they resolve to uncover the true killer before Gayathri closes in. Vasu suspects Malathi of exploiting the situation to seize Radhika’s wealth, and Malathi eventually admits she had known all along that the girls had been fooling her. The shocking disclosure: the young man who posed as Ramesh was really Vikram, a family friend Malathi had intended to marry to Radhika. Through their college circle, the girls learn that Geetha had gone missing on the night of the murder. They track her to a border town, where Geetha reveals she, too, was on the run from Gayathri; she had returned to the hostel to fetch medications and had inadvertently witnessed Gayathri kill Vikram/Ramesh. Geetha fled, fearing Gayathri’s influence would erase the truth.
Just as Gayathri seems to close in, the woman who had posed as Ramesh’s mother arrives and is revealed to be a CBI officer investigating Gayathri, who understands that the three girls are not responsible for Vikram’s murder. The truth fractures Gayathri’s composure, leading to a mental breakdown. The revelation is stark: Gayathri murdered Vikram to avenge her sister’s paralysis after Vikram assaulted her sister. To escape accountability, she framed Vasu and Radhika for the crime. The film concludes with Gayathri institutionalized in a mental asylum, while Vani, Radhika, and Geetha, now close friends, visit her and reaffirm their bond.
