Denning is an American mercenary enlisted by some Hong Kong nationalists. He has just lost $25,000 at the local bar, so the nationalists recruit him to stop the Communist threat. Gates runs the bar, the Green Dragon, and unwittingly has been helping the Commies in their efforts to take
over Hong Kong. Denning and a couple of buddies help expose the Red plot. Naturally, their efforts come not a second too soon; a bomb floating on a raft has been set to explode in the city's sewage system. Action is plentiful and the pace is fast enough to hold interest throughout.