Plot

Flat No 4B narrates a few real life incidents. Revathi (Swarna Thomas) is a teenager hailing from a middle class family. As her father Raghu loses his job, circumstances force him to take up the job of a security at a flat. In the meantime, Revathi falls in love with Manu, who one day takes her to his flat -- the same flat where her father works as the security. Following events form the rest of the plot.