Tom Swift's his most resent invention, the Timescope, is a device designed to look into the past to let people watch as history unfolds on a monitor. He hopes to return to the Mayan temple deep in the Yucatan to test it on symbols carved on the walls that look like ones sent from his Space Friends. At first his request is refused, but he gets the permission he needs. A rogue scientist has Tom's sister kidnapped in an effort to force Tom to give him the device, tries to ruin Tom's reputation, stop him from ever getting to Mexico, and even uses dynamite to trap Tom and his friends in the temple. With the aid of Harlan Ames and a team from Swift Enterprises, he finally sees what he came to find. On returning to Shopton, Tom and Bud are ruthlessly attached by their enemy. This is the story about how Tom perserveres in his hopes to bring a new took into the hands of history buffs, archeologists and even the police, even against the wish of an ultra-conservative politician and his followers.