After the death of their newborn son, Lieutenant Colonel Ziganshin and his wife Frida adopted three children. Frida immediately accepted and fell in love with them, but Ziganshin does not succeed, the children remain strangers to him and do not help relieve the pain of loss. And now his wife has no time for him, she is absorbed in maternal concerns. To escape from melancholy, Ziganshin is actively involved in the investigation of an explosion in the house of a famous professor, and it seems that other people's family secrets will help him understand himself and rethink a lot.