Cold Fusion (2)

Cold Fusion (2) begins with the squad stuck in their own building. Boyd's HQ has been placed under lock-down by the anti-terrorist squad, and the team is kept in quarantine until the substance that affected Dr Felix Gibson can be identified. That's the whole set-up, and a neat inversion of the usual formula: for once the mystery isn't buried in an old grave, it's sitting in the room with them.

Being confined does things to this lot that no suspect ever managed. Routine stops dead. Grace can't work her files, Spencer can't chase his leads, and Boyd, a man whose entire method involves barging through institutional walls, is told to sit still by people with better protective equipment. There's a dry pleasure in watching professional frustration curdle in a sealed room while scientists argue about what the compound actually is. The tension comes from the lack of space rather than the size of the case.

Trevor Eve leads as DSI Peter Boyd, with Sue Johnston's Dr Grace Foley and Wil Johnson's DI Spencer Jordan alongside him. Esther Hall is back as Dr Felix Gibson, the one who took the hit from whatever the substance turned out to be, and Félicité Du Jeu is DC Stella Goodman. David Calder plays Commander Bill Drake and Paul Copley is Clifford Day, with Mark Lewis Jones as Tom McQueen, Abhin Galeya as Harry and Mark Letheren as Toby Holmes filling out the quarantine.

Richard Standeven directed, from a script credited to Barbara Machin and Ed Whitmore. It's essentially a bottle episode wearing a biohazard suit, and the writers clearly knew it: strip away the crime scenes and the morgue, and you're left with characters who have nothing to do but talk, worry and get on each other's nerves.

An outside threat locking the Cold Case Squad out of its own investigation is a good joke at the show's expense. Whether the answer justifies two episodes is another matter, but the confinement itself earns its keep.