‘Why are you doing it? What are you trying to protect? What are you fighting for?’ A script that plays to the show’s strengths, with a focus on Gwen and Rhys’ relationship impacted by Torchwood; Gwen putting her police skills to practice to solve a mystery, and real lives intersected by the Cardiff rift. The result is easily Chibnall’s best work for the series, and a template of sorts for Children of Earth, with Jack’s involvement in a longstanding cover-up.

It’s also the kind of episode that benefits from the show having some history behind it, so that PC Andy’s comments about Gwen growing harder since she joined Torchwood carry some weight. This begins as Gwen reconnecting with her roots as a decent police officer, empathetic and doggedly persistent, pulling in Tosh and then Ianto into her investigation into the missing of Cardiff. These sequences are helped by an outstanding guest performance by Ruth Jones as Nikki Bevan, mother of one of the rift’s victims, but the most credit is with Eve Myles brilliantly moving between Gwen’s confrontations with Jack and Rhys, and the growing horror when the scale of the disappearances becomes clear.

The only downside is the episode – like much of Torchwood, to be fair – depends on Jack refusing to share information with people he’s meant to trust. Had he explained the situation to Gwen earlier, and had he been clear about the nature of Jonah’s specific predicament, a lot of angst might have been avoided. Instead, he’s inexplicably cagey and the result – predicably, given he couldn’t conceal the truth from Gwen from Everything Changes – is that she blows the cover-up wide open.

But this lapse doesn’t undermine the power of the final scenes, as Jonah retreats into the trauma of his experiences, Nikki realises it’s sometimes better to live in hope, and Gwen wonders whether anyone has benefited from her involvement. Often these unresolved questions and pyrrhic victories can end Torchwood episodes on a bum note, but here it feels earned and appropriate. You wouldn’t want a whole series like this (or you might, if you enjoy stuff like Millennium), but this ends up as one of Torchwood’s triumphs.

Next Time: Fragments