Major Tarasov is instructed by the front headquarters to create and lead a reconnaissance group consisting of Italian and Russian circus performers. The circus troupe successfully works behind enemy lines, carrying out the most dangerous and daring tasks of the Soviet headquarters, until their fate changes with the accidental appearance of a dwarf in the troupe. His unique abilities attract the attention of the Gestapo. The Nazis brutally deal with members of the circus troupe after learning about their subversive intelligence activities. Miraculously, the three surviving artists are taken to a secret fascist laboratory located high in the mountains, in a castle. There, Soviet intelligence officers will face an unequal confrontation with a German professor, whose monstrous experiments on people amaze and frighten any consciousness.