Luther, BBC One

Idris Elba’s screen career is going so swimmingly that you wonder what can have tempted him back to Blighty. Probably not the weather, since the former denizen of Canning Town now lives in Florida, and is in perpetual demand Stateside thanks to the extreme hotness engendered by his portrayal of Russell “Stringer” Bell in The Wire.

So, Idris Elba, where did it all go wrong? I jest, of course. Slightly. Luther is perfectly watchable, beautifully shot, and indeed quite diverting. Elba broods majestically, when not throwing people across the room or smashing doors with his bare hands. Snag is, the plot is ridiculous, and a batch of rather fine actors have been persuaded to throw subtlety and logic to the winds and to portray characters which veer wildly between cliché and implausibility, rarely reaching any kind of equilibrium in between.

Elba’s pivotal role of DCI John Luther was surely constructed by writer Neil Cross by raiding a graveyard filled with the crumbling bones of old detective series. Luther is a maverick, a loose cannon, a man on the edge who breaks the rules to get results! We learn this immediately, since the opening scene consists of Luther ferociously pursuing his quarry (serial child killer Henry Madsen) around an abandoned factory. Finally he has Madsen at his mercy, hanging from a girder by his fingertips several floors up. Luther won’t offer any help to the panicking felon until he reveals the whereabouts of his latest victim. Then, once he has divulged this information, Luther still can’t bring himself to lend a helping hand, and watches as Madsen plummets to the concrete floor below.

The action proper begins after Luther has survived an official inquiry by virtue of “exceptional circumstances” (wisely, nobody tries to explain this in any detail), though nemesis is left lurking in his peripheral vision by the knowledge that Madsen is in a coma, so might wake up at some point in the remaining five episodes and spill the beans on Luther’s churlish behaviour.

Cross's tactic is to leave no ‘tec tic unticked, and he has supplied Luther with the de rigueur failing marriage. His wife Zoe (Indira Varma) still loves him, you understand, but she can’t stand any more of his professional obsessiveness, the way he gets all morbid and driven in his relentless pursuit of murderers and rapists. She has taken up with Mark North (Paul McGann), a rather insipid human rights lawyer who has to fend off the raging Luther when he comes battering at the door like an angry water buffalo tormented by hornets.

Luckily, crimes keep being committed in order to keep Luther occupied. He’s soon checking out the cold-blooded murder of a middle-aged couple and their unfortunate family dog. Luther interrogates their daughter, Alice Morgan (Ruth Wilson, pictured below, playing it 1,000 degrees foxier than she did in Jane Eyre), and teases out the information that she is a former child science prodigy with a PhD in astrophysics.

This tees up some clonkingly mechanical banter about dark matter and black holes, with which Luther displays an astonishing degree of familiarity, venturing the observation about dark matter that “we know it’s there, but we can’t see it.” Just like Ms Morgan’s guilt, as it turns out, which Luther brilliantly reveals when he tricks her into not yawning empathetically at the same time as he does.

So, since we knew whodunnit within about 15 minutes, the mainspring of the plot has become how Luther can prove the precocious Morgan’s guilt before she can devise another perfect murder with him as the victim. Already she has shown us a vivid gallery of wigs and threatened Mrs Luther by sticking a hatpin in her ear, and the way she used a Glock pistol made of polymer as a murder weapon and then shoved it inside the dead dog to be cremated was a fiendish touch.

Who will prevail, the cool and ruthless Alice Morgan or the intuitive but unstable Luther? I can’t say, but I could have a darn good guess.