Mrs Carol Speeder

In the novel Destination Unknown,  Mrs Carol Speeder is an American woman who purportedly works for the UNO. Shortly before the disappearance of Thomas Betterton, she called the Bettertons and invited them to London for a lunch. According to Thomas' wife Olive Betterton, Thomas declined the invitation. She was surprised when British security officials later told her that Thomas had gone ahead to meet Mrs Speeder at the Dorset hotel in London where she was staying.

British security officials like Mr Jessop were working on the premise that Betterton might have defected to behind the Iron Curtain. Mrs Speeder had been questioned by the Committee of Investigation into un-American activities. She managed to clear heself but Jessop thought she could nonetheless be a foreign agent.

It later transpired that she is a recruiter working for Mr Aristides with the mission of attracting talented scientists to join his secret research station. Andrew Peters heard about Speeder when she made overtures to a friend of his. Peters met up with Speeder and made use of her in his efforts to join the Aristides station.