The heroes of the film are first-graders Snezhana and Alyosha Seroglazov, who received the nickname "TwoBriefcases" because of his small stature on the first day of attending school, as well as a small puppy Kysh.

Based upon the story by R. L. Stevenson, the film shows Orson Welles as Long John Silver, pirate chief, who would like to find hidden treasure.