What a curious confection Death Valley is. It’s as cosy as crime drama gets and yet, thanks to its show-within-a-show concept, it manages to be oddly arch and knowing, too. Its body count challenges that of The Sopranos, but in its soothing episodic rhythms and Welsh valley quaintness, it remains as comfortable and predictable as Christmas.

As we return, everything and nothing has changed. Janie Mallowan (Gwyneth Keyworth) has been promoted to detective inspector and is wondering if her seniority means she can no longer call herself “J-Dog”. She remains charming but also goofy and tactless; at one point, she complains about a teabag being left in a cuppa made for her by the wife of a recent murder victim.

Meanwhile, John Chapel (Timothy Spall) is a long way from the gloomy recluse of old. In fact, he’s positively chipper, almost as full of self-regarding quips as his erstwhile TV detective alter ego, Caesar. He’s now knocking boots with Janie’s mum, Vonnie (Melanie Walters) – “I did try not to,” he says indignantly. Janie isn’t having this and, as a result, John is persona non grata down at the police station. But clearly, this state of affairs will not last. After all, what provincial police force worth its salt could resist enlisting the help of an ageing but still universally recognisable actor to help them crack homicide cases? Not this one.

Death Valley’s main strength remains its willingness to lean into the absurdity of its premise. Across this second season, stories include everything from a suspicious death in a community service litter-picking detail (inevitably, Chapel is forced to don a hi-vis bib and pretend he has committed a driving offence to get the inside track on the group) to the murder of a hipster chef selling seaside street food.

The cases are variable in entertainment value but never in depth or weight – each one is as light as a feather and as gentle as a pillow. They rely on cheerful cameos from guest stars who include Alexandra Roach, Jane Horrocks, Jim Howick and Roisin Conaty. Each crime is solved via a series of hilariously stagey deductions and the climactic reveals veer dangerously (deliberately?) close to self-parody as Janie and John take it in turns to dole out their revelations.

The plotting is ridiculously schematic throughout: Death Valley sometimes feels less like a cosy crime drama and more like a snarky spoof of one. But you’ll be inclined to forgive its surfeit of eye-rolling moments, mainly because of its trump card, Spall. As he becomes more windy and verbose by the episode, you understand that you’re watching a man breezily engaging in one of the least subtle roles of his career and, very probably, one of his most enjoyable. Crucially, he and Keyworth have excellent chemistry, animated by just enough affection and antagonism. Thanks to them, Death Valley is supremely comfortable in its own skin – entirely undemanding but contentedly so.

It’s also relaxed enough to self-critique relentlessly. Once you start noticing these internally referential Easter eggs, it’s hard not to see them everywhere. John rails against “the current level of banality in most mainstream TV drama”. Janie describes John’s performance as “a bit hammy”. A suspect describes one of their reveals as “needlessly theatrical”. All of these meta-judgments check out: on all counts, Death Valley is guilty as charged and bang to rights. If scenery-chewing and excessive exposition were crimes, we’d be locking it up and throwing away the key.

But still, who’s to judge? Really, just the audience, and Death Valley offers audience service in spades. Not every TV cop show has to be as grave as Line of Duty or as expansive as Blue Lights. There is only one thing that can’t be forgiven in a cosy crime drama and that is a lack of character. If the crimes themselves are simple, that’s a feature, not a bug. The twists and turns of a cleverly constructed investigation would get in the way of the core narrative, which remains the odd but sweet central relationship.

Chapel’s entire detective persona (as Caesar and as himself) revolves around deducing “character inconsistencies” in suspects. But as far as he and Janie are concerned, there aren’t any. Death Valley simply has its daft, sometimes painfully sweet cake and eats it. Consumed as part of a balanced diet, it’s just fine.