MCDB is actually about three thieves, Kalicharan and his two sidekicks, Puti and Baka who decide to rob and go back to their old tricks after Kalicharan is released from jail. They decide to rob the occupants of the Mitra household which comprise of an elderly man, Pradosh Mitra, his two sons and their families. They decide to carry out the robbery at a time when the house will have no occupants according to information received by them. Accordingly they act, but are they successfull? Well, no, because unknown to them, Pradosh and one of his grandsons, 7 year d old Som have decided to stay back and create havoc for them. All their efforts to rob the house are in vain as little Sohom turns out to be more than a handful for all of them!