While accompanying Pete's inventor grandfather to New York where the old man plans to sell his new invention, the Three Investigators find themselves in the middle of a dangerous spy case.
Wealthy eccentric Charles Barron is convinced that aliens are planning to fly to earth and take him away. The detective trio resolves to prove that Barron is being taken for a ride--but not by hostile aliens.
When an ornery book collector disappears, the Three Investigators break into his secret computer files in search of clues and gradually uncover his mysterious past.
