A skip tracer--someone who collects late payments from people who've purchased appliances, etc., or takes them back them when they don't pay--repossesses a small radio from a deadbeat who's skipped payments. What he doesn't know is that a gang that has stolen diamonds from a Hollywood movie star has stashed them inside the radio, and they start hunting for him.

Hans Memling, a young intellectual, patriotic German, is secretly opposed to the Nazi regime. With the aid of Gustav Schultz, Father Pommer, Anna Wahl and others, he is gleaning accurate information from foreign radio broadcasts and distributing it through Germany with an underground-press operation.