On 16 November, 1941 at the La Dessa U. S. army post in the Philippines, a Japanese carrier ship off the coast transmits a coded message to the contraband radio of Nazi spies. The spies then stick the message, which states that a Tokyo battleship is approaching Pearl Harbor, to a bottle of German liquor called Kümmel. Just then, the womanizing private Steve "Lucky" Smith meets his fellow soldiers Bruce Gordon and "Portly" Porter in the Casa Marina bar, and Lucky and Steve both try to attract a beautiful woman, who soon informs them she is Portly's sister Marcia. Portly arranges a job for Marcia as the secretary to Andy L. Anderson, the owner of the bar. When a businessman named Littlefield slips into Marcia's booth and bothers her while reading the message on the bottle of Kümmel, Lucky defends her by attacking Littlefield, and Bruce and Portly join the fight. Captain Hudson disciplines the three by assigning them to find the spy's radio.