Perhaps it was inevitable when a TV show is a huge as The Walking Dead that we'd get a spin off. In terms of ratings, Fear the Walking Dead is already a success and had the highest viewing figures for any first season of any series on cable in the US. BT also used it as the main selling point for the launch of their exclusive AMC channel.

It opens with a familiar set up; a grungy warehouse as Nick Clark (Frank Dillane) wakes bleary-eyed from a drug-induced stupor and stumbles into a zombie chowing down on his friend. Obviously freaked he runs for his life into the street and the camera pulls back to reveal traffic and life going on as usual. It's a neat trick, we're so used to post-apocalyptic ruins infested with the undead that normal life looks weirdly out of place in the WD universe.

Fear is pleasingly different from its parent show. We jump across the country to LA and back in time to the very start of the zombie outbreak. It's something we've never seen before as the population come to the slow realisation that the dead are coming back to life.

Thrown together by adversity a new band of survivors are drawn together. Madison Clark (Treme's Kim Dickens) and Travis Manawa's (Cliff Curtis) relationship is already complex: a couple who both have teenage children from previous marriages. Madison's eldest Nick is a mess, still searching for a fix even as the army quarantine their home; Travis' son, Chris (Lorenzo James Henrie) is torn between his mother and father rebelling against their control. Throw in a handful of zombies and you have an emotional powder keg as civilisation starts to disintegrate. The uninfected are herded into camps, fences erected around their homes, cut off from the world and information: a breeding ground for paranoia.

Human drama is at the centre of Fear. Inevitably as it charts the beginning of the epidemic there aren't many zombies. Their existence drives the entire plot but the undead only make cameo appearances in the first few episodes. It's even brave enough to feature an episode without a single walker. Remarkably it's the tensest instalment of the entire run. As a consequence they become a real threat once again, we're so used to Rick and co taking on the shambling hordes with grim gusto it's nice to see a single zombie striking terror.

There are almost too many characters to introduce over such a short run (just six episodes) that many are reduced to flimsy stereotypes (there's also a family from El Salvador and a sharp talking millionaire in the mix). Dickens and Curtis are both fantastic, their anxiety and desperation in protecting their dysfunctional family unit is palpable. However the teens don't fare so well and Dillane is particularly annoying mainly because his character is so self-absorbed.

Unfortunately the final episode is frustrating. While we don't want to give the game away it features a rescue plan that is illogical and incredibly selfish, that conflicts with pretty much everything the characters have stood for up until that point, for the sake of action (and if you've been concerned by the lack of zombies through the series there are literally hundreds in this season finale).

Fear The Walking Dead has already been commissioned for a second season, and it'll struggle to justify its existence as it moves into more familiar territory as the undead make their presence felt. There's real potential focusing on a different group of survivors, but the battle to keep Fear from being a shallow facsimile of its parent show is only just beginning.

Fear the Walking Dead, Entertainment One, is available from Mon 7 Dec.