Multistorey (1)

Series three opens with a case aimed straight at Boyd's softest spot. A man accused of opening fire on a crowd from a multi-storey car park, killing a policeman in the process, is claiming his innocence. Ordinary enough as cold cases go, except for one detail: among the dead was Boyd's close friend. And Boyd, for once, seems in no hurry to re-investigate anything.

That reluctance is the engine of the episode. His colleagues start questioning where his loyalties lie, and it's hard to blame them. Boyd's whole method rests on pushing past other people's grief to get at the truth, and here he's the one flinching from a reopened wound. Barbara Machin and Ed Whitmore wrote it, Robert Bierman directed, and they let the discomfort build without rushing it.

The best material belongs to Claire Goose. DC Amelia Silver starts digging into why her boss won't touch the case, and what she turns up about him is genuinely disturbing. Watching a junior officer quietly investigate her own superior gives the hour a second mystery running underneath the first, and Goose plays it with exactly the right mixture of loyalty and dread.

Around them, the supporting cast fills out the original atrocity and its aftermath: Robert Pugh as Robert Cross, Jason Hughes as Andrew Cross, Kim Vithana as Beth Downing, Sean Pertwee as Carl Mackenzie and Lara Cazalet as Fiona Mackenzie. Sue Johnston, Holly Aird and Wil Johnson hold the fort as Foley, Wharton and Jordan while their leader wobbles.

It aired in September 2003, and it makes for a strong season opener precisely because nothing about it is comfortable. The question isn't only who did the shooting. It's whether Boyd can be trusted anywhere near the answer, and by the end of this first half you're not sure he can. Neither, it seems, is he.