Wonder Woman takes on a Japanese spy named Ishti.
Diana is surprised and jealous to find Steve Trevor spending time with a red headed woman, Dolly. She overhears him telling General Darnell that he is going to New York to follow a clue, but Diana believes that he just wants to spend time with Dolly. She visits Steve on the train to New York, dressed as Wonder Woman, but doesn't learn much more about what is going on.
A brief scene then reveals that Dolly is in fact planning to double cross Steve in order to get a code key for a Japanese spy named Ishti. The spy threatens to kill Dolly if she doesn't go through with the plan.
Now in New York, Diana confronts Steve, warning him against seeing Dolly. Steve refuses to listen. After they leave Steve's room, Diana hears noises and looks through the keyhole to find a bunch of men searching the room. They don't find anything, but Wonder Woman stows away in their car. They go deep into the subway tunnels beneath the city to their secret headquarters with Wonder Woman in tow. She learns that Ishti agent and his men have set mines beneath the railway lines, and intend to detonate them when the U.S. High General is on a train traveling on those lines. In order to know when the High General is on the train, though, they need to crack the code from the telegraph wire that they have tapped. Ishti claims that Dolly will get the code key from Steve that night. When they finish explaining their plan they spot Wonder Woman, but she escapes.
Wonder Woman then learns that Dolly is performing in a show called "Manhattan Scandals." Betting that Steve will be there, Wonder Woman attends and even takes the stage. She shows the audience the power of her Lasso of Truth and tries to catch Steve in it but he gets away. She finds him backstage with Dolly and he appears to be drunk and to hand over the code key. Steve leaves and Dolly hands over the code key to Ishti.
Wonder Woman arrives after the spies have left and confronts Dolly. Dolly tells her where the agents have gone, but they give Wonder Woman the slip. Ishti returns to Dolly and gives her a perfume that will knock Wonder Woman out. Wonder Woman calls upon Etta Candy and the Holiday Girls for help, then returns to Dolly who does, indeed, knock her out with the perfume.
Ishti has learned from Baroness Paula Von Gunther that Wonder Woman will be powerless if a man attaches chains to her bracelets, so he has one of his men do just that. They then hook her up to an electrical device and intend to shock her to death, but she switches the current so that it passes through her without doing any harm.
Steve, meanwhile, reveals to his men that he has been pretending to pursue Dolly, and that he gave her a fake code. He and his men are actually the ones on the train, and they intend to lure the enemy spies into a trap, believing that the spies intended to board the train and take the High General prisoner. Etta Candy joins them.
Ishti, however, is not planning to board the train as Steve believed, but intends to blow it up. Wonder Woman is desperate to escape. Fortunately, the person who forged her chains becomes distraught upon learning what Ishti is planning to do and removes the welder's mask covering her face, revealing that she is a woman. Since a woman forged the chains, Wonder Woman is not powerless and she breaks free of her chains. She races to the train tracks and uses the chains that had bound her to short out the tracks, causing Steve's train to stop. Steve and his men, with the help of Wonder Woman and Etta Candy, then capture Ishti and his men.