Broadchurch, STV, 9pm

Is it slacking? Is the huge outpouring of admiration that marked the return of Chris Chibnall's blockbuster police drama on the wane? Not on the evidence of the four episodes so far, which have seen Joe Miller (Matthew Gravelle) plead not guilty to the murder of Danny Latimer, the case his police detective wife Ellie (Olivia Colman) spent the entire first series trying to solve in the company of her irritating superior officer Alec Hardy (David Tennant).

Chibnall's reintroduction of Joe in episode one was a stunning coup de theatre and allowed him to bring in actresses Marianne Jean-Baptiste and Charlotte Rampling as rival barristers Sharon Bishop and Jocelyn Knight. And everyone loves a court-room drama, right? Well, everyone except bereaved parents Mark and Beth Latimer (Andrew Buchan and the excellent Jodie Whittaker), and those like Ellie Miller who have face cross examination and the humiliating allegation that she and Hardy were having an affair.

In tonight's fifth instalment, Ellie and Hardy continue their investigation into the unsolved Sandbrook murders, which were referred to only tangentially in the first series but which have become a central theme here thanks to the arrival in Broadchurch of Hardy's main suspect in that case, Lee Ashworth (a menacing James D'Arcy).

But as we learned in last week's episode when he returned to the scene of the crime and learned a few new facts, Hardy is now starting to entertain doubts about Ashworth's guilt. Those doubts increase tonight when Ashworth's ex Claire (Torchwood's Eve Myles) produces her third version of events surrounding the murder of the two young girls. Those who thought all along that Claire was a little fishy will be punching the air in vindication, even though her new version seems to incriminate Ashworth even more. Mind you, she isn't the only character with something to hide: the re-appearance of static caravan-dwelling ne'er-do-well Susan Wright (Pauline Quirke) brings one of the series one's most villainous characters back into the frame. Elsewhere Sharon Bishop, who is left despairing after Jocelyn Knight destroys Wright's credibility on the witness stand, finds help from an unexpected source, local reporter Olly Stevens (Jonathan Bailey) lands a major scoop, and Ellie has a heart-wrenching scene alone with her estranged son Tom (Adam Wilson).