In the decadent and dangerous Shanghai of 1929, someone is spying for the Japanese, and the International Settlement's British police are on the hunt. Now, in the midst of the Mid-Autumn Moon Festival, American aviator Jack "Ace" Jordan becomes the prime suspect. Embarking on a desperate bid to clear his name, Ace joins forces with a local drug dealer, an aspiring news reporter, and a rescued Chinese teen to unmask the identity of the true agent...