A young man, RC Franklin, travels with a group of rag-tag musicians that include his mother and father. Prior to World War II German U-boats trained near the coastline of Atlantic City, New Jersey. RC Franklin meets a young showgirl named Ruby after her horse-diving act on the Steel Pier, and Ruby turns out to be a German spy working under cover while leading a group supplying whiskey to U-Boats offshore to bolster the morale of sailors on long deployments from the Fatherland. Ruby uses petty crime that escalates into major crimes including her charms as a beautiful young lady to ensnare RC into the spy ring. RC wrestles with the decision to turn-in the spies for espionage but he gets dragged deeper and deeper into a plot with tragic results for many innocent persons.