True Detective review: Mahershala Ali is compelling, but he's let down by this bloated drama

At the start of its third series, it is clear that True Detective, HBO’s noirish procedural drama, is dogged by that old entertainment dilemma: do you give the audience more of what they liked before, or try something new?

In the programme’s debut run, the buddy-ish relationship between Matthew McConaughey and Woody Harrelson’s detectives helped leaven the gloom as they investigated macabre crimes in Louisiana. For its second season, it swapped the stars for Colin Farrell and Rachel McAdams, and the setting for Los Angeles. It was a valiant attempt to have a continuity of tone, rather than personnel and plot – but the results were patchy. Neither the new leads nor the setting clicked. True Detective was a mood piece, and that darkness was entwined with its geography. The flat open spaces and sparse population helped create a sense of civilisation stretched so thin that cracks were starting to appear.

For series three, which airs in the UK on Sky Atlantic, they have returned to the deep south, this time to the Arkansas Ozarks (also of Ozark fame). The cast has changed again. Mahershala Ali stars as Wayne Hays, a Vietnam veteran turned detective. He has a partner, Roland West (Stephen Dorff), but the focus is on him as he investigates – guess what? – a macabre crime, after two children go missing on a bike ride. There are three separate time periods: the original events, a reinvestigation, and a filmed interview for a true-crime documentary, set in the recent past. In each period, Ali is compelling as a professional trying not to let his memories get the better of him.

On the evidence of the first episode, however, it looks as though he may be let down by other elements. With its rolling forests and body part-evoking place names like Devil’s Dam and West Finger, the setting does its job. The dialogue shows glimpses of masterful restraint and black humour, as in a funny and revealing exchange, after Hays stops West from assassinating a fox, about which animals make acceptable hunting targets.

But the plot takes a long time to get going; an hour, for events that would be over in the first five minutes of another show. Despite this, the supporting cast feel underdeveloped next to Hays. He meets Amelia (Carmen Ejogo), who will become his wife and a significant figure in the story – but she is relegated to the background.

In other words, while some of the innovations are welcome, some of the returning features feel tired. Viewers are fickle monsters. If we feel we are about to be taken down a road we’ve travelled before, it’s difficult to get invested in a whole new set of companions. At this point, it is easier to say what True Detective is not than what it is. It is not a simple murder mystery, it’s not quite a character piece, and it’s not a buddy drama. If you don’t know what people want from you, it’s hard to know what to be.