Back review: Series two of Mitchell and Webb's latest sitcom was worth the wait

Blackwell's sitcom picks up with publican Stephen Nichols (David Mitchell) receiving treatment at a psychiatric institution after being pushed to the brink by his manipulative foster brother, Andrew (Robert Webb). Stephen is discharged after duping the doctors into believing he has attained a new outlook on life, but in reality, his bitter resentment has only grown stronger. The trouble is that Andrew remains a very popular figure among the rest of the Nichols family, so any attempt to expose his true nature is going to take some careful planning.

The story of Back revolves around this volatile rivalry, so it's hard to imagine better casting than Mitchell and Webb. The duo have been working together for some 25 years but their chemistry hasn't lost any of its punch.

The cynical and pedantic character of Stephen plays very close to Mitchell's usual comedy persona, but he does it so incredibly well that it's really hard to care. There are moments in series two where he commands such an electric hold over the screen that it's hard to take your eyes off it, delivering gleefully vitriolic rants in the way only he can.

On the other hand, Webb gives a genuinely unsettling performance as Andrew, masterfully depicting a sinister and superficial form of kindness, that only exists to serve his seemingly limitless Machiavellian schemes. Indeed, it's easy to drop your guard to his charms from time to time, which only makes it more shocking when the next twist of the knife comes.

Both are captivating individually, but of course, it's a joy to watch them share the screen, with one episode set during a pub quiz featuring a particularly gripping confrontation.

Where previous Mitchell and Webb projects have relied almost solely on the comedy duo themselves, Back is blessed with a superb supporting cast that features several standout performances. Geoffrey McGivern frequently steals scenes in the role of Stephen's uncle Geoff, an eccentric farmer who is never shy about sharing his outrageous (and hilarious) opinions on the world. Meanwhile, Penny Downie is an unsung hero as Ellen, the matriarch of the Nichols family, a character she plays with this twitchy intensity that seems to add a unique cadence to each line delivery.

They might be the standouts among the cast, but there isn't a weak link to be found here. It is simply an ensemble firing on all cylinders that becomes more endearing with every passing episode. If one of the tenets of sitcom writing is that the principal characters can't fundamentally change, Blackwell's scripts do a very sophisticated job of exploring them within that tight restriction. Olivia Poulet's Alison benefits most from this treatment, enjoying a fascinating story arc that adds new dimensions to her role.

Not every joke hits the bullseye, but there can be no denying Back is a very sharply written show. It's a witty sitcom first and foremost, but its intriguing overarching story also utilises elements from mystery thrillers and family dramas to great effect. The final scene of each episode always brings something new to the table that will have you hooked into the next instalment, with added pizzazz offered by some impeccable end credit song choices.

It all culminates in an unexpectedly downbeat finale - which might not sound like a glowing recommendation in regard to a sitcom - but in fact, it's a testament to the writing and the caliber of the performances that series two plays out in such an affecting way. It also quite brilliantly sets up a potential third run, so hopefully we won't have to wait quite as long for Back to be back once more.

Back series two premieres on Channel 4 at 10pm on Thursday 21st January. Looking for something else to watch? Check out our TV Guide to see what's on tonight.