A Communist sleeper agent in New York has just been activated. The sleeper is known to the FBI and is being watched. But shortly after being activated, the agent has a heart attack. Erskine goes undercover, assuming the man's identity. His target is an operative known as Minerva, who is operating out of Pittsburgh. But the assignment has more than the normal risk. There's a power struggle under way among the spy ring. Minerva has recorded a set of tapes that he believes will be his "insurance policy." For Erskine and the bureau, those tapes are an opportunity to gain valuable intelligence about spies operating in the United States.
—Bill Koenig