Aye, the nights are fair drawing in, as we say round these parts (although not so much in Marchmont or Morningside) and it’s that time of year when the programme schedulers know that’s there’s nothing we like more to huddle out of the rain and watch than a good murder.

Scotland is, on one analysis, a Nordic country (certainly the Vikings left a lot of genetic material round these parts) so it’s unsurprising that our crime dramas feature grim-faced characters blundering around in the gathering dark just as much as our Swedish and Norwegian cousins. Ian Rankin has long been our premier exponent of such stuff with his Rebus series, and it is he who has scripted an interesting variation on the usual, with real live people, Bake-off style, being put on an island and asked to solve a crime while bobble-hat and chunky sweater wearing actors play the suspicious locals, acting suspiciously.

However, innovative as Murder Island might be, it is perhaps unfortunate it’s on at the same time as the latest series of Shetland, a completely fictional crime drama involving a Scottish island, a murder, suspicious locals in bobble hats, and lots of sheep.

It in turn is unfortunate in sharing a similar release schedule with Guilt, a comedy crime caper set in Edinburgh which, although not set on an island, shares many of the same principal actors as Shetland. Confused? You will be, as they used to say. You keep expecting Mark Bonnar, in his Shetland role, to come out with some dry comedic line that ties in with his very Edinburgh character in Guilt. Right up until he doesn’t. And then there’s his somewhat feckless wee brother in that, who’s not in this series so far, probably because he’s busy being a passed-over and therefore slightly embittered cop in Annika, which I haven’t even mentioned yet. And don’t even go there with the now-finished Vigil, the Scottish-based murder on a submarine…

Anyhoo. In the interests of being helpful, I thought I could maybe try and summarise the storyline of the first two of these without getting mixed up. Although I fear I may have failed:

In Murder on the Islandland, DI Jimmy Perez returns to his native turf to investigate the thoroughly nasty end of a local lawyer. A man. Or it could be a woman who was an environmental activist. Or it could have been both: I mean, who knows what goes on on the Mainlandland these days?

The locals are understandably shocked. It’s a tight, well-knit community, with only occasional, albeit regular, homicidal impulses. Who wanted the victim dead?

It’s no surprise that it turns out to be just about everyone. There’s a local barman who worked in the Big City on Mainlandland and may have got her (or him) pregnant. There’s a dodgy businessman who’s simultaneously buying up most of the locals’ landholdings and supporting somebody’s wife to become an MP. When Perez asks him why, even the businessman looks unconvinced when he says ‘putting something back?’

There’s drugs, and all that dirty kind of Mainlandland stuff. And a local hoodlum who can generally be contacted by going into the local dive bar where he’ll be playing the puggie (1). Incidentally, it always amazes me that these kind of low-level bad guys are always in the pub but are still able to function well enough when it comes to casual threats against potential witnesses or high speed chases along remote single-track roads. Maybe they’re lime and soda kind of guys.

Whatever. DI Perez, who’s one of those rumpled, tousled, monosyllabic types of uncertain age that younger women generally find irresistible for plot purposes, has his usual team to draw on: the female deputy that looks a bit sceptical all the time; the barrel chested seen-it-all desk sergeant Billy; and Sandy (pronounced Shandy) who generally has little or no agency but has to be there as he’s the only one with a convincing Shetland accent.

Perez spends much of the first episode staring moodily out at the bleak seascape, perhaps yearning for a simpler time when he could just get Billy to take the main suspect round the back and beat a confession out of them. But wait! What’s this? The Procurator Fiscal from Mainlandland may appear to be as welcome as a fart in spacesuit, but she’s managed to source some extra team members: perhaps some sort of a Supported Employment scheme by the Scottish Government.

So Perez can also count on the lovely lady who you’d absolutely want to have as your next door neighbour and look after your plants when you were away, and her slightly bossy actual next door neighbour; the two brothers-in-law who have the same haircuts and dress in weirdly identical outfits (I mean, what is that about? Your brother in law, right?) and an ex-professional footballer and his fiancee who are definitely the best dressed, and also seem to have most of a clue about how to investigate a crime (albeit we’re talking a low bar here, folks).

Soon they’re clambering all over the island, asking daft questions of the suspicious locals, leaving Perez to stand brooding against stone-and-mortar cottages or the ever-darkening sky. Shandy gets himself run over by the local hoodlum, who’s showing off his driving skills to an alcoholic mother, and there are so many unlikely relationships of both the blood and other kind going on even the sheep are starting to look sceptical.

Whodunnit? Who cares, really, when everyone’s having so much inbred fun, but I’d bet my bobble hat on the most middle class character in both series. It’s usually them, greedy for more money. Unless it’s not of course, and it’s someone who turned out to be someone’s auntie’s daughter by their second marriage who changed their name and lived on Mainlandland for a while and got into drugs and all that sort of nasty Mainlandland stuff that goes on. It could be them.

Or it’s the two brothers-in-law working under deep cover. I mean, my brothers-in-law wouldn’t be seen dead in the kind of stuff I wear.

(1) fruit machine