Brahmachari is a comedy movie in which, Sambhandam (Kamal Hassan) is a wealthy guy who finds job satisfaction as the stunt master for film. He feels that marriage disintegrates the man's character and strength. Janaki (Simran) is a doctor cum feminist, who feels that man is the source of all evils.
Anand (Abbas) is a friend of Sambhandam. Malathi (Sneha) is the friend of Simran. Anand and Malathi fall in love and they get married to each other against the wishes of Sambhandam and Janaki. Janaki trains Malathi in such a way that Malathi and Anand divorce for some differences.
In an incident, Sambhandam gets injured in a minor accident. Janaki, who accidentally drops in a musical watch in the stomach of Sambhandam, operates him. Janaki realizes it later. The rest of the film is all about how Janaki seduces Sambhandam to love her so that she injects anesthesia and take that watch out.