Raoul Walsh, best remembered for his rough-and-tumble action pictures, made this film on a rare loan-out to a British studio. Jim Tracey (Wallace Ford) is an American gangster who, while on the run from the law, flees to England, where he joins the British army by posing as a Canadian. Jim and his new friend Bert Dawson (John Mills) go through training together, and they both get to know Sally Briggs (Anna Lee), the daughter of their commanding officer. While Jim and Bert vie for Sally's attentions, Jim discovers that his girlfriend Jean Burdett (Grace Bradley) has followed him to England and is threatening to reveal his true identity. Jim ships out to China with his regiment before Jean's word can get too far; it turns out that Sally is also on board the ship, but that bit of good news turns sour when band of Chinese bandits attempt to seize the ship and take Sally with them. O.H.M.S. was also released under the more American-sounding title You're in the Army Now.