Swinging playboy Grand Duke Nicholas Wladimirovitch Goduno (Marcello Mastroianni), a direct descendent of the Romanov family who were overthrown in the Russian Revolution of 1917, learns that his family's crown jewels will be exhibited at a London museum and plots to steal them. To this end, he gathers a crew of beautiful but dangerous women, led by Bridget Rafferty (Rita Tushingham), to assist in his plot against Popov (Warren Mitchell), the Soviet functionary in charge of the exhibit.