Shanghai, 1929. War in Asia is on the horizon. Great Britain, Japan, and Russia, the biggest players in the city, are already fighting secret battles, each trying to gain the advantage and willing do anything to get it.
The British Secret Service has hatched a daring plan to steal the latest model of Japan's Enigma machine, and hide the loss from the Japanese with a deception operation. If the Secret Service plan does work, the machine would give Britain the key to decoding the most secret Japanese messages.
For reasons he doesn't understand, Jake Greenberg, the owner of a fashionable casino, has been chosen by a mysterious foreign agent to act as a go-between. Reluctantly he agrees to do it when authorities threaten his business, but his experience with the British Secret Service has not been good.
Soon the Secret Service plan begins to fall apart. The Japanese and the Russians have their own sources and know more than the British realize. Jake's friend, a young man new to secret operations, is killed. Then another key figure is murdered, shot on the street and left to die. Fearing exposure as their plan slips toward disaster, the Secret Service refuses to investigate or even acknowledge their deaths. Not Jake. Convinced that there is a traitor among the British team, he begins to hunt down the killer.