FBI agent James Belden (George Murphy) is tasked with finding and bringing down a communist spy ring operating in Boston. After an anonymous tip, Belden and his agents tail a man who leads them to various suspects, as they try to determine how far the espionage reaches. Meanwhile, the spies force a scientist (Finlay Currie) to divulge secret information by holding his son hostage. As the investigation continues, it seems the Russian agent Alexi Laschenkov (Karel Stepanek) might be behind it all.
Shelf Location: D5