Masha Alentyeva, nicknamed Mucha, herself did not expect that she would spend her holidays in the Paradise Bush sanatorium with the children of rich people and artists, deputies and ministers. Only her “luxurious life” is developing strangely and dangerously: fights with strangers in masks, a listening device found in the room... Revealing the secrets of her mysterious opponents, Masha learns that the robbery of the century is being prepared at the sanatorium...