Three friends in a summer camp are looking for a treasure hidden in a old mansion.

A Red Army officer Polevoy possesses a navy dirk with a secret message encrypted in its handle. The second part of a message belongs to a White army officer Nikitskiy. It's up to three young friends of Polevoy to uncover the mystery.

In the beginning of WWII a group of five brave children are fighting the Nazis in Belarus.