A woman writing a scientist's biography is mistaken for a spy.

Jennifer Nelson, a young widow working in the public relations office of a space laboratory, meets her new boss Bruce Templeton when he accidentally catches his fishing line on a mermaid outfit she is wearing while entertaining tourists on her father's glass-bottom boat. Templeton, delighted to discover that the woman he "fished out" of Catalina Bay is working at his plant, assigns her to write a definitive biography of him while he is test-piloting a new rocket. Jenny's habit of "exercising" her dog Vladimir by telephoning him at home (he runs around the house whenever the phone rings), arouses the suspicions of CIA men. When she overhears Templeton discussing the possibility that she is a foreign spy, she makes misleading phone calls at a party at Templeton's home. Unknown to her, a secret formula has been planted in her purse, and the real espionage agent pays her a visit when she arrives home. Jenny bolts out of a window and a mad chase follows. The real culprits are apprehended, and Jenny ends up in her boss's arms.