FBI agent Ireland tries to thwart a communist plot while vacationing at Big Bear resort. The trouble begins when atomic scientist Craven is murdered by his traitorous assistant Larsen, who steals Craven's important papers. Donlon, Ireland's girl friend (who is also Malone's sister),
witnesses the crime and grabs the papers to sell herself. She is killed by Larsen, who is also eventually killed. Ireland wraps up the case.