The film is a historical drama set during the reign of Elizabeth I (Flora Robson), focusing on the English defeat of the Spanish Armada, whence the title. In 1588, relations between Spain and England are at the breaking point. With the support of Queen Elizabeth I, British sea raiders such as Sir Francis Drake regularly capture Spanish merchantmen bringing gold from the New World.

On the sidewalks of the London theater district the buskers (street performers) earn enough coins for a cheap room. Charles, who recites dramatic monologues, sees that a young pickpocket, Libby, also has a talent for dancing and adds her to his act. Harley, the theater patron who never knew Libby took his gold cigarette case, is impressed by Libby's dancing and invites her to bring Charles and the other buskers in his group to an after-the-play party. Libby comes alone. A theatrical career is launched.

In 19th century Russia a woman in a respectable marriage to a senior statesman must grapple with her love for a dashing soldier.