The British Admiralty is worried: several cargo ships carrying troops have mysteriously jumped off Gibraltar. The Admiralty calls in the Intelligence Service to find out the cause of the destruction before new units arrive. Lieutenant Jackson, of the Marine Infantry Regiment stationed in Gibraltar, spends all his duty time in Tangier, where he is attracted by his love of poker and a beautiful dancer, Lola. Despite the objurgations of his general and the tender friendship of Cathie, his general's daughter, he can't stop playing and loses a very large sum one evening.