Undertow (2)

The worst possible thing happens in Undertow (2): the team turns out to be right, and it changes nothing in time. Steven Hunt, their prime suspect, drowns two more young girls while the squad is watching him. Under surveillance. With the release date still coming.

That failure is what gives part two its weight. Part one asked whether the team could prove their suspicions before a non-violent offender walked free; part two answers by showing what their proof is worth against a man who kills anyway, calmly, under their eyes. The clock stops being an abstraction. Every hour Boyd and Grace spend building a case is an hour Hunt spends being exactly what they say he is.

Oliver Brown and Barbara Machin wrote it, David Thacker directed. Trevor Eve is Detective Superintendent Peter Boyd, with Sue Johnston as Grace Foley, Wil Johnson as DI Spencer Jordan, Esther Hall as Dr Felix Gibson and Félicité Du Jeu as DC Stella Goodman, and Sharon Duncan-Brewster as Sarah Baker. Stephen Moyer makes Hunt properly chilling, the sort of quiet menace that makes you believe the surveillance was never going to be enough. Cheryl Campbell as Maureen Hunt, Peter Wight as Donald Hunt and Dan Fredenburgh as Ben Elwes fill out the family around him.

The episode's bleakest idea is that watching is all the law allows. The team can see the danger clearly and still has to wait for him to act, because suspicion has no custody rights.

It lands hard. Few episodes of this show make the procedure itself feel like an accomplice, and this one manages it without a speech. Moyer plays Hunt as a man who knows precisely how much rope the law must give him, and uses every inch of it. Against that, Boyd's fury has nowhere lawful to go.

The Hunt family material deepens things too; Cheryl Campbell and Peter Wight make the horror of living near suspicion feel domestic rather than dramatic.

Undertow earns its title by the end. Everyone watching this man gets pulled under with him.