At a space laboratory meeting presided over by naval liaison officer Arthur Nordlund, scientists involved in a research project on human endurance are warned by fellow member Henry Hallson that one of them possesses a super-intelligence capable of controlling other minds and effecting destruction through sheer willpower. None of Hallson's co-workers--including biochemist Jim Tanner, geneticist Margery Lansing, physicist Carl Melniker, chairman N. E. Van Zandt, and biologist Talbot Scott--is convinced until Hallson is found murdered with the name Adam Hart scrawled near his dead body. Tanner, Insp. Mark Corlane's chief suspect, begins an investigation of his own and learns from Hallson's widow, Sally, that her husband had a childhood friend named Adam Hart. Although Tanner loses his job at the laboratory, he persists in his search as one by one the other members of the research group are killed off, Tanner himself barely escaping death at the hands of the mysterious force. Eventually Tanner learns that Nordlund (alias Adam Hart) is the villain, and that he hopes to conquer the world for the sake of "good." Tanner, who also possesses a superhuman brain, finally summons sufficient strength to destroy Nordlund.