The surest way to work out who dun it, in a whodunit detective series like Shetland (returning to BBC2 for a second series), is to note any familiar-looking character actors who pop up early on in the investigation. BBC casting agents don't pay top dollar for a face unless they know they'll be getting their money's worth.
We were odds-on, then, that Magnus Bain (played by the craggy-faced Emmy-winner Brian Cox) would turn out to be a chief suspect in the murder of a young woman, and we would have been confident in our guess, even if he hadn't also been a reclusive, creepy old man who kept a raven as a pet and repeated the ominous catchphrase: "It's not my day for that."
Bain was also living in the same wind-swept shack 19 years ago when a much younger girl called Catriona went missing on the island. Catriona's body, unlike Catherine's, was never found, but there appeared to be similarities between the cases. This is already a bizarrely high murder rate for such a small community, but we'll just have to suspend our disbelief – there are still five more episodes of this series to go.
Statistically speaking, this remote Scottish archipelago might be an unlikely setting for a crime series, but, atmospherically, there's nowhere better suited. The islands' strong Scandi influences allow Shetland to incorporate some of the glowering mood of Nordic noir while remaining reassuringly home-grown, mostly thanks to the comforting presence of Douglas Henshall as Detective Jimmy Perez. No, Perez isn't a Shetland name, but that's just part of his romantic enigma. "They say a ship wrecked from the Armada and a Spanish sailor fell in love with a Fair Isle girl."
It's these unexpected touches that set Shetland apart from its peers. In contrast to the ghoulish norm in TV drama, the script made a careful point to note that the young female victim here hadn't been sexually assaulted. "I've never known a girl be killed and that not be one of the rumours," said Perez when asked about the case by his teenage step-daughter. "In this case, I can assure you, it's pure speculation."
Perez was likewise desperate to avoid the easy option of arresting oddball Bain, but, in this case, surely the most obvious solution is also the right one? It was a two-parter, so we'll have to wait till next week to find out.