Wonder Woman reluctantly agrees to star in a Hollywood movie in an effort to inspire America. She agrees to go in part because she learns that Steve Trevor is in California searching for enemy agents.
Upon arrival, Diana meets Yvette, a maid who has been assigned to Wonder Woman. Yvette sees Diana's bracelets at the same time that Diana sees the marks on Yvette's arms indicating that she is one of Baroness Paula Von Gunther's slaves. Diana slips away so that she can arrive in Hollywood a second time, this time as Wonder Woman. Knowing that Yvette works for the Baroness, Wonder Woman pretends to drink some tea that Yvette prepares, then acts as if she is drugged. She catches Yvette trying to steal her lasso, but when Yvette sees Wonder Woman's bracelets she realizes that Wonder Woman and Diana Prince are the same person. When Wonder Woman threatens to use her lasso to force Yvette to reveal the Baroness's plan, though, Yvette drinks poison so that she won't betray her Mistress.
The first day of filming begins and Wonder Woman is to be bound, put in a trunk, and lowered into the ocean with a fake bomb attached to her. She realizes that the bomb is real and that the actors tying her up are in fact Nazi spies. She narrowly escapes the explosion, but is unable to capture the Nazis, who get away on a speed boat.
Meanwhile, Steve Trevor is following two men who have been posing as Chinese, but whom he believes to be Japanese agents. They take a boat to a very small island, but when Steve arrives on the island they are nowhere to be found. On Wonder Woman's advise he returns to the island that night, but since he did not head her warning to go with an army of men he gets captured, but not before realizing that the island is in fact an invention of the Baroness and can rise and lower in the water the same way that a submarine does. The enemy agents are able to go inside the island when it is underwater.
Wonder Woman learns of Steve's disappearance and sets out to find him, but a group of extras from the film intercept her and whisk her away to their yacht to celebrate her coming to Hollywood. They wrap her in flowers that turn out to be drugged, as they are, in fact, agents of the Baroness.
At the same time, Wonder Woman has given her magic lasso to Etta Candy, who has followed her to Hollywood, with instructions to question Ben Black, the director of Wonder Woman's film, as she believes that he is an enemy agent. Etta captures Ben Black and forces him to lead her to Baroness's island base.
In that base, the Baroness is holding Wonder Woman prisoner, preventing her escape by threatening to drop a massive weight on Steve Trevor's head if she tries anything. The Baroness is planning to make Wonder Woman her slave, but Etta Candy and the Holiday Girls arrive and free Steve Trevor, thus allowing Wonder Woman to break free and help capture the Baroness.