Magdalene 26 (1)

Series eight opens with a woman running naked along a country road, picked up without a memory to her name. She is well-off and plainly lost, and she cannot say how she got there. That leaves the squad with two cases at once: the immediate one, which is how she ended up on that road, and the older one, because her DNA turns up in a cold case from more than forty years back, one involving two bodies and a sword.

But the two investigations refuse to stay tidy. Around the amnesiac woman the links fan out. The case takes in a car accident and her husband's bizarre murder, and somebody looted his company in the aftermath. The episode has to hold the confusion of the present against the slow burn of history, and it manages the balance well, letting the woman's missing memory stand in for everything the case cannot yet explain.

Barbara Machin and Declan Croghan wrote it, and Andy Hay directed. Trevor Eve leads as DSI Peter Boyd, with Sue Johnston as Dr Grace Foley and Tara Fitzgerald as Dr Eve Lockhart, Wil Johnson as DI Spencer Jordan, Félicité Du Jeu as DS Stella Goodman and Stacey Roca as DS Katrina Howard. Sharon Maughan plays Elizabeth, Lisa Dwyer Hogg the teenage Elizabeth, Elizabeth Barrett the young Elizabeth, and Denise Gough Kathleen.

The amnesia is a smart device. It stops the woman from simply explaining the case away, and it forces the team to build the story from the DNA and the clothes, none of which agree with the cold file. That gap between what a person says and what the evidence says is where this show has always lived.

A season opener needs a hook, and this one has plenty: a naked woman with no memory and a murdered husband, with a sword in a forty-year-old grave thrown in for good measure. It is a lot to carry, and the writers carry it lightly enough that the pieces stay interesting on their own terms. The answers can wait until part two.