Major Phillip Waring, the head of the Cipher Bureau in Washington, D. C., is called away on the day of his wedding to secretary Helen Lane by an urgent request to decipher a diplomatic message intercepted from an international spy ring.

With the spy's death, their only clue is a letter written in Chinese, which they give to Bureau interpreter Artie Johnson to decipher.

Johnson's information sends Waring and Murdock to California on a wild goose chase.

In their absence, however, Helen finds Johnson's blotter and realizes that he is involved in the spy ring.

Meanwhile, Waring realizes that his mission is a frame-up, and returns to Washington to discover Helen's peril.