By the time you front up to the sixth season of a police procedural like Shetland, you have to ask yourself: has this run its course? I found the fifth season of Shetland to be brilliant, centered on the galvanic intensity of Douglas Henshall as DI Jimmy Perez, and I’m pleased to report that, all expectations to the contrary, Season 6 is another dose of the same but even more powerful. In this season, a popular lawyer is gunned down on his doorstep, a huge roster of suspects includes his wife, a rich businessman, and an ex-soldier with PTSD. Throw in Perez’s mother’s death and the dementia of his father, and the return of a previous season’s murderer with terminal cancer, and the plot is wonderfully baffling. The supporting cast of Alison O’Donnell and Steven Robertson as sidekicks Tosh and Sandy, plus Mark Bonnar as friend Duncan, is as strong as ever, but it’s Henshall as Perez who draws the viewer in. Once upon a time he looked like a hunk, now he has fleshed out and has the visage of a haunted obsessive. Breathe in the first five episodes of Season 6, crime fiction lovers, then gird yourselves for a transcendent final episode in which Henshall gives you a Jimmy Perez triumphant but at the end of his tether. Me, I was left breathless.