Arriving on a resort muscovites - circus artist Gurov and professor Fedorov are forget the houses of passport. Girl-dispatch on mail, hurrying on an appointment, mixes up envelopes, that entails the row of the comic misunderstanding.

After news of the future birth of a child, Sergei split from his wife, Natasha, and settled in the company of young architects, who occupied a room in a big house. As a result of a chain of unforeseen events, brought by one of the tenants found a child, Sergei finds a newborn son. Friends are doing everything possible to find a lost mother, but Sergei does not disclose their affiliation and tries to give the baby the wrong hands.