11.22.63, Fox / NOW TV

If this were a British series it would be called 22.11.63, since the title refers to the date on which President John F Kennedy was assassinated in Dallas. Anyway, this is a TV version of Stephen King's hit novel, and its mix of historical conspiracy and time-travelling sci-fi is perfect fodder for its producer, JJ Abrams.

You have to swallow a fairly hefty portion of disbelief to allow yourself to get into the story, namely that the homely neighbourhood diner in Maine run by Al Templeton (Chris Cooper) has a porthole through time hidden in the pantry. Every time you walk in there, you're instantly transported back to 1960. You can spend years in the past, and when you return to the present only a few minutes will have elapsed. After each visit the portal, Groundhog Day-style, resets itself, so next time you go back you start again from scratch (Al's diner, below).

As we embarked on this opening episode, The Rabbit Hole, our protagonist knew nothing about any of this. He's Jake Epping (James Franco), who teaches English to schoolkids as well as running an evening class for a motley bunch of students in need of a general education qualification. Jake is in the middle of divorcing his wife, so we can make allowances for his melancholy demeanour. He's often to be found in Al's diner, eating hamburgers and marking course papers.

All this gets tipped on its ear when Al, who has inexplicably gone from being perfectly healthy to a terminal cancer sufferer in a matter of minutes, lets Jake in on his time-busting secret. More than that, he explains how he has been working on a plan to go back to the Sixties and prevent the assassination of JFK. His illness won't let him complete the task, but he manages to talk an incredulous and disbelieving Jake into taking over the job.

Not all that likely, you'll probably agree, but the idea is tantalising enough to pull you into the aforesaid rabbit hole just to see what happens. Also, Cooper conveys tremendous conviction in Vietnam veteran Al's idealistic belief that if he could prevent Kennedy's death many of the subsequent catastrophes and wrong turns in American life might have been avoided (he might be wrong, but he's plausible). As for Franco, he delivers a winningly sympathetic portrayal of a man who feels he's a mere spectator as his life drifts past him, and discovers a cause worth battling for in this outlandish timewarp scheme (below, Sarah Gadon as potential love interest Sadie Dunhill).

Director Kevin Macdonald and his crew have had fun recreating the early Sixties with a fizzing mix of clothes, buildings, advertisements and music, from primitive rock'n'roll to Frank Sinatra's special Kennedy-promoting version of "High Hopes" ("Jack is on the right track!"). Delicious chrome-finned cars abound, with Jake sliding behind the wheel of a covetable yellow Chevrolet.

In a dark suit and fedora hat, Jake is transformed into a man with a mission as he starts getting enmeshed in the knot of conspiracy theories surrounding JFK's death. Was Lee Harvey Oswald really a lone gunman? Was he a Russian agent being run by the mysterious emigré George de Mohrenschildt? How much did the CIA know? And who are the mysterious characters who keep popping up to warn Jake that "you shouldn't be here"? A cracking start.