Hot on the heels of Wallander and The Killing, The Bridge hit British screens in 2012 at the height of our Scandi noir obsession. The first season introduced us to Swedish detective Saga Norén (Sofia Helin) and her Danish counterpart Martin Rohde (Kim Bodnia), who were forced to work together to find out who had placed the head and torso of one corpse and the legs of another at the point on the Øresund Bridge where Copenhagen meets Malmö.

He was laid-back and sarcastic, she was rules-obsessed and blunt to the point of rudeness due her difficulty picking up on social cues. (When Martin invited her to dinner and his wife Mette offered to give Saga the recipe, she responded: “No, it wasn’t tasty.”) Their opposites-attract dynamic might not have been original, but the characters’ quirks and their emphatically platonic chemistry made it feel fresh.

The shocking end to season one, when the serial killer they were tracking picked Martin’s son for his last victim, threatened to rock the show’s foundations. But it came back stronger than ever, combining a storyline about eco-terrorism with Martin’s search for vengeance and Saga’s awkward attempts to support him, which ended tragically when he poisoned his nemesis and she turned him in. After that, she needed a new partner, and the show went off the rails.

Martin’s replacement, Henrik Sabroe (Thure Lindhardt), was pleasant enough but also gulped handfuls of illegal drugs from a sandwich bag before work and spent his evenings at singles nights, even though he had a wife and kids at home. Or did he? Four episodes into season three, the show revealed that his family had gone missing years earlier and we’d just been watching his hallucinations. Not only was this a betrayal of fans’ trust, it signified a dismaying shift in focus.

While the detectives’ personal lives had always been part of the story, now they threatened to take over – and in the most improbable ways possible, such as at the end of season three, when Saga’s mother killed herself and framed her daughter for murder. The central mysteries were similarly difficult to stomach, including victims with amputated body parts staged in grotesque tableaux, a stoning, and a man tricked into injecting his daughter with a lethal neurotoxin.

Never the most fast-paced show, it became increasingly ponderous and took the cliched route of putting Saga and Henrik in a relationship. When he dumped her after she had an abortion without telling him, she renewed her efforts to find his missing relations, eventually reuniting him with his surviving daughter – a turn of events that had the unfortunate effect of seeming as if she needed to atone for exercising her reproductive freedom. The final scene saw her fling her detective badge from the eponymous support structure in a gesture that was coded as triumphant, but which made little sense for a character who had always found hope and meaning in her job. It was the final nail in the coffin for viewers’ hopes that The Bridge might return to form.