Hellfire

Walpurgis night, and Glasgow is anything but peaceful. James Martin is murdered with a chainsaw, in circumstances that drag in witchcraft and Satanism. Detective Scott investigates the case and cannot catch the prime suspect. At his own retirement party he collapses, and his plea to Taggart is simple: bring the people responsible to account. The chainsaw murder is the kind of opening image that tells you this will not be a gentle hour, and the episode leans into it without winking. The gothic mood is laid on thick, and the show clearly enjoys it.

Reid is working deep undercover, and she has started to suspect her target is actually innocent. That is the kind of doubt that keeps an undercover officer awake at night. She learns that Gregg Martin's ex-girlfriend has withdrawn her statement against him, but she keeps digging anyway. A withdrawn statement is not an acquittal, and Reid knows the difference. Undercover work is lonely, and the episode lets that loneliness show. But then the local shopkeeper, Mr Brodie, is killed, and the hunt for his killer begins. Each case feeds the others, and none of them waits its turn.

Glenn Chandler wrote it, Marcus D.F. White directed. Mark McManus is Taggart, James MacPherson is Jardine, Blythe Duff is DS Jackie Reid. Greg Wise is Gregg Martin, Isla Blair is Lavinia Martin, Bill Murdoch is Bill Scott, Gray O'Brien is Rob Gibson, with Iain Anders as McVitie, Robert Robertson as Dr Stephen Andrews and Harriet Buchan as Jean Taggart. A solid regular line-up behind a story that keeps piling on the strange.

The Satanic trappings are there, but the episode is really about unfinished business. A retiring detective handing his burden to the next man, an undercover officer doubting her own target. It is a strong way to open a season, and it sets the tone for what follows.