Stephen Neale is released into WWII England after two years in an asylum, but it doesn't seem so sane outside either. On his way back to London to rejoin civilization, he stumbles across a murderous spy ring and doesn't quite know to whom to turn.

A Nazi spy ring is after a chemical formula that increases the power of ordinary gasoline for U.S. Army aviation use. Two U.S. chemical companies are developing the formula, with each working on half for security purposes. The spies get half the formula and know that either of two chemists, Robert Norton or Tom Fielding, knows the rest. They capture Fielding, through a ruse by gang member Linda Pavlo, and threaten the life of his sister Nancy and his mother if he does not give them the formula. To protect his friend Fielding, who does know the formula and is engaged to Nancy, Tom pretends to know the secret and boards the Dawn Express plane with the spy leader and his gang.

A small-town reporter investigates a mysterious group holed up in a country lodge.

Allied spies and Nazi Agents insinuate themselves at a Scottish cottage (converted to a wartime hospital) with interests on an inventor's nearly perfected bomb sight.

The Lone Wolf tracks down Nazi spies in London during the German bombing.

Bank accountant Thomas Lieven is forced to work as a triple agent for the British, the French and the Nazis.

A British man is hunted by British and German spies when he tries to sell blueprints.

The obsessive scientist Dr. Miller is working on a matter-transmitter invention called the Paratron; a conspiratorial team of spies and no-goods pursue him to Alaska, trying to steal the device.

An intrepid radio reporter sets out to track down and expose Nazi agents.

Broadway gamblers stumble across a plan by Nazi saboteurs to blow up an American battleship.

A Nazi spy passes himself off as an optometrist in San Francisco's waterfront district. Someone robs him of his code book, and he must get it back.

Ole discovers Nazi spies planning to take over the ship he's working on.