Cela fait près de 30 ans que le Dr Sam Beckett est entré dans l'accélérateur de particules et a disparu. Aujourd’hui, une nouvelle équipe, dirigée par le physicien Ben Song a été constituée pour relancer le projet dans l'espoir de comprendre les mystères derrière la machine et l'homme qui l'a créée. Après avoir effectué un saut non autorisé dans le passé, Ben se retrouve à son tour dans une spirale temporelle, passant de vie en vie et d’époque en époque. It's been nearly 30 years since Dr. Sam Beckett stepped into the Quantum Leap accelerator and vanished. Now, a new team, led by physicist Ben Song, has been assembled to restart the project in hope of understanding the mysteries behind the machine and the man who created it. Everything changes, however, when Ben makes an unauthorized leap into the past, leaving the team behind to solve the mystery of why he did it. At Ben's side throughout his leaps is Addison, who appears in the form of a hologram only Ben can see and hear. She's a decorated Army veteran who brings level-headed precision to her job. As Ben leaps from life to life, putting right what once went wrong, it becomes clear that he and the team are on a thrilling journey. But they also know that if they are going to solve the mystery of Ben's leap and bring him home, they must act fast or lose him forever.