text: In 1917, former newspaperman William Gordon  enlisted in the U.S. Army. The day before he is to leave Washington, D.C. for the fighting in Europe, he meets socialite Joel Carter . The couple spend the day together. He tells her that, because he once wrote a book on cryptography under a pen name, the army is searching for him to put him to work behind a desk, but he is eager to fight the Germans. The next day, just before he boards his train, Lieutenant Gordon is ordered to report to John Carter , the Assistant Secretary of War. He reassigns the unhappy Gordon to Major William Brennan  to spend the war decoding German transmissions. He learns that Joel had revealed his secret to her uncle, John Carter, in order to keep him around. The U.S. is preparing to send its army across the Atlantic Ocean, but there are grave worries about the U-boat threat. Brennan comes up with the idea to have British escorts meet American transports before they enter the most dangerous zone. For maximum security, the rendezvous point is to be transmitted in code to the ships the day before. An ammunition ship is sent first to test the new system. Unbeknownst to the Americans, a German spy ring in the city has already cracked their code and deliberately allowed the ship through in order to lure more valuable troop transports into their trap. However, when Gordon manages to decipher one of their messages, he realizes the truth and alerts his superiors. Brennan suspects his supposedly unbreakable code was stolen by his mistress, Olivia Karloff , and sets a trap. He catches her red-handed, but foolishly he is alone, and she shoots him dead. To her dismay, she is ordered to sacrifice herself to divert suspicion from the spy ring. When she attends Brennan's funeral, Gordon has her brought in for questioning. Carter sees her enter Gordon's office and becomes very jealous. Gordon lets Karloff go free so that she might lead him to the rest of the spies. The Germans decide to betray one of their own men, Captain Nicholas Nieterstein , in order to reassure the Americans and get them to resume operations. When he is arrested at the Russian Embassy, Nieterstein apologizes to Ambassador Gregory  for giving his loyalty to his mother's country before flinging himself through a window to his death. Afterward, Gordon escorts a shaken Karloff back to her hotel, where he discovers her guilt. However, since the hotel is staffed by German agents, he is the one who is captured. He refuses to divulge the new American code until they show him that Carter is also a prisoner; she had followed the pair to the hotel. He then gives in and provides the coordinates of the new rendezvous point. When the Germans transmit the information, it is decoded by the Americans. The latitude and longitude that Gordon had given are actually the address of the hotel. Gordon and Carter  are rescued. They get married.