Frank Keyes joins a group of “Seventeen Learned Men,” embarking upon a dubious prehistoric voyage “70 Million Years in the Past.” The voyage is plainly a hoax. A laughable publicity stunt. But promoter and financier Sir Lionel Lytton claims to have mastered time travel itself, and established a small colony within the Cretaceous world. Sir Lionel’s voyage departs from Mackinac Island, Michigan, at which time Keyes discovers that Lytton’s claims are not as laughable as they seem. . .