Un extraterrestre assassina al jove Agent K l'any 1969, alterant la línia espai-temps i posant en perill el planeta Terra. El veterà Agent J haurà de tornar fins a aquell any, hores abans del crim, per salvar l'agent, l'Agència, la Terra i, de retruc, tota l'Humanitat. Mentrestant, l'actual Agent K espera nerviós que l'assumpte es resolgui favorablement, perquè ell seria el primer damnificat.
Theorizing that one could time travel within his own lifetime, Dr. Sam Beckett stepped into the Quantum Leap accelerator and vanished... He woke to find himself trapped in the past, facing mirror images that were not his own and driven by an unknown force to change history for the better. His only guide on this journey is Al, an observer from his own time, who appears in the form of a hologram that only Sam can see and hear. And so Dr. Beckett finds himself leaping from life to life, striving to put right what once went wrong and hoping each time that his next leap will be the leap home.
A mysterious criminal steals a secret state-of-the-art time machine, intent on destroying America as we know it by changing the past. Our only hope is an unexpected team: a scientist, a soldier and a history professor, who must use the machine's prototype to travel back in time to critical events. While they must make every effort not to affect the past themselves, they must also stay one step ahead of this dangerous fugitive. But can this handpicked team uncover the mystery behind it all and end his destruction before it's too late?
It's the 30th century and time travel is illegal. To help monitor and police time crimes, the Time Protection Department is founded. But when Don Dolnero and his nefarious gang manage to trick four new TPD cadets into allowing them travel to the 20th century, the four cadets are forced to pursue them for the sake of history. There, in a time foreign to them, the cadets enlist Tatsuya Asami, a young martial artist, to aid their mission. Together, these five youngsters become the Timerangers. And though they try to live as ordinary 20th-century citizens, the Timerangers dedicate their lives to stopping Dolnero and others that may follow in his footsteps, attempting to forever alter the proper timeline!
