Engineer McLean, the prince's wife Shirvanskaya and his lover Rumanescu, who came to the Soviet Union, pretend to be circus actors and act to the detriment of the country. Arranged as a worker in the oil industry, Rumanescu steals blueprints of a military invention from the chemist Petrov. Tom Jackson discovers that the circus performer and the saboteur John are one and the same person. Saboteurs,...