Time Bomb — Franklin W. Dixon

A TWIST IN TIME...A TWISTED MIND...A TERRIFYING TWIST OF FATE FOR FRANK AND JOE AND TOM!

A dream that has long fired the human imagination has become a reality: time travel. But as Tom Swift and the Hardy boys are about to discover, the dream can become a nightmare in the blink of an eye. An attack force of techno-thugs, under the command of the evil genius the Black Dragon, have seized control of a top-secret time-warp trigger!

Frank and Joe and Tom leap into battle -- shock troops in a war that stretches across the aeons to the edge of time. But whether chasing asteroids or dodging dinosaurs, they know they haven't a moment to lose. They must stop the Dragon before he carries out his final threat: turning the time machine into the ultimate doomsday device!