Wren Boys (2)

Part two picks up the concrete boy case and starts squeezing. The injured Joe McDonagh finally wakes from his coma, which should crack everything open, except what he can actually remember of a boxing bout that went badly wrong years ago turns out to be a much smaller key than everyone hoped.

The shape of the mystery settles into something uncomfortably domestic: Boyd works out who was at the centre of it, but the killer could be any one of four people, McDonagh father or son, or Killigan father or son. Two families, two generations, and a dead teenager in wet concrete between them. That's a better puzzle than most cold cases manage, because every candidate has a plausible reason to have been there that night and none of them can afford the truth coming out. There are also surprises in store for Boyd and Spencer Jordan along the way, and the episode spends them well rather than hoarding them for the last five minutes.

Trevor Eve is DSI Peter Boyd, with Sue Johnston as Dr Grace Foley and Tara Fitzgerald as Dr Eve Lockhart. Wil Johnson's DI Spencer Jordan gets his share of the fallout, and Félicité Du Jeu is DC Stella Goodman. Carey Mulligan plays Sister Brigid, Edward MacLiam is Joe McDonagh, Tony Scannell plays Papa McDonagh and Daragh O'Malley is Sean Killigan Snr, with Ruairi Conaghan as Sean Killigan Jnr completing both family trees.

Declan Croghan and Barbara Machin wrote it; Tim Fywell directs again after part one, keeping the tone steady while the story turns on itself.

What I like about this half is that the answer matters less than what the answering costs. A coma waking up sounds like a plot device, and here it mostly produces more silence. Old men protecting sons, sons carrying fathers' fights, an abbey quietly holding all of it. Waking the Dead at its best does generational rot very well, and this is the show doing exactly that.