An elderly man - a naive, impractical artist of the musical comedy theater - writes an operetta about goodness. His son is a resuscitation doctor, very businesslike and practical, and teases him all the time. The marriage of Petrov Sr. to the young ballerina Alena also did not add harmony to their relationship. But one day, father and son suddenly realize how necessary they are to each other... When the young stepmother begins to be in danger during childbirth, the son stops being sarcastic and fulfills his human and filial duty.