There's no shortage of real-life crime shows out there. Most of it is awful US tabloid TV, like Blood Relatives, I (Almost) Got Away With It and Wives with Knives. Stuffed with clunky re-enactments, interminable waffle from self-styled criminal behaviour analysts and syrupy voice-overs for the hard of thinking, they barely justify the claim that they are documentary programmes.What a welcome surprise then to stumble across The Murder Detectives (BBC Brit, Channel 120 DStv), a gripping three-parter built around the apparently motiveless and fatal stabbing in March 2014 of a 19-year-old Bristol student, Nicholas Robinson. Like Netflix's Making a Murderer, it is superb "long-form" television; unlike Making a Murderer, however, it feels like a scripted drama, a police procedural along the lines of Silent Witness or Waking the Dead.There is, however, nothing of "glamour" or artifice here. No dysfunctional cops with messy back-stories, no sexy pathologists, no laconic detectives acting on whims. In fact, the cops here couldn't be more unlike those found on cop TV shows.Their work is hard, thorough, routinely boring, banal and exhausting. Their biggest ally is technology. We open with Robinson's taped call to a police hotline: "Oh, f***ing hell, I've been stabbed really bad." A few garbled curses later he dies.And so starts DCI Andy Bevan's investigation. It involves watching hours and hours of CCTV footage, ploughing through cellphone records, meticulous laboratory work, relentless searching for clues. It's slow, grinding stuff. And all of it was made available to award-winning director David Nath and his team, along with access to daily police briefings, conferences and suspect interviews. No aspect, it would appear, of this 18-month saga, which ended with a conviction, was left unrecorded.The style of this fascinating series is quite filmic, from close-ups of exhausted cops' faces to the gritty feel of Bristol's back streets. Tension quickly builds, thanks to superb editing and an excellent score, and at times you have to remind yourself that this is all real, that there's a very human tragedy at the heart of all this.The second episode of The Murder Detectives is screened tonight, and it concludes next Friday. BOX POPSWENTWORTHEXCELLENT Australian prison drama series focusing on Bea Smith (Danielle Cormack), a woman convicted of the attempted murder of her husband. (M-Net Edge, Channel 102 DStv)VIKINGSRAGNAR Lothbrok (Travis Fimmel), Norse scourge of England and France, and his band of warriors return for an epic, 20-episode fourth season. (M-Net Edge, Channel 102 DStv)..