Barah Aana is a comedy of real life set in today's Mumbai. The story revolves around three unlikely friends: a driver (Naseeruddin Shah), a watchman (Vijay Raaz) and a waiter (Arjun Mathur). The driver is an older man, stoic but dependable. The watchman, in his 30's, is a pushover at work but otherwise mischievous. The waiter is a young, swaggering chap, brimming with ambition. Living together, their different attitudes make for an interesting banter.

At some point, misfortune befalls the watchman, and due to a series of chance events, he stumbles into a crime. Striking upon a seemingly low-risk way to make good money, and discovering a new sense of self-confidence, he tries to entice the others to join him in a series of such crimes. Cat and mouse games ensue between the three as personalities change, but events soon spiral out of control, leading them in a direction that none of them had ever wanted to take...