Messiah V: The Rapture BBC1, 9pm

DOWN Messiah's mean streets walked Walker (DCI Joseph of that ilk), an hombre whom life had treated most meanly. Unsurprisingly, Walker wore a less-than-generous look on his taut, blank-eyed face. Walker: he may well be the world's most dogged, solitary, sinned-against and quietly agonised detective. Making his Messiah debut in the show's fifth stylishly realised outing, the ever-compelling Marc Warren played him as a haunted automaton, instinctively conducting his copper's duty because it's all that's keeping him going.

For Walker is doomed to walk, alone, through a harrowing wilderness of permanent pain. Mostly his own pain, although other people had lots of the stuff as well in last night's opening segment of an inventive and involving two-part gore-fest.

Walker's pain stemmed from having been unwittingly involved in a suicide bombing at a checkpoint on the Gaza Strip. Did his Palestinian freedom-fighter girlfriend, Salma, know in advance that her brother was going to detonate himself in a crowd of people seconds after stepping out of Walker's car?

Walker tortured himself with images of the searing terror-blast; saw other folks' blood on his hands; wondered whatever happened to Salma in the deadly explosion's aftermath; pledged never to trust anyone again.

Luckily for Walker, there was plenty hapening to keep his mind off such hellish ruminations. An ultra-busy, theatrically-minded murdering machine was loose on his patch! First, a Muslim family of four were slaughtered and ritualistically posed at their dining table. Next, two young Jewish women were dressed in men's suits and stagily hanged in their homes.

In a spooky car park, a Christian woman fell victim to a monstrous hooded symbolist who put her eyes out with acid. At each murder site, ominous cabalistic symbols were drawn in a pile of sand - sand from a specific region of Israel - left on the floor.

Seven victims, from three different Abrahamic religions. Those curious hieroglyphs, spelling out the ancient Hebrew word for God. That sand from the Holy Land: what could it all mean?

Revelations! Genesis! Exodus! It suddenly became clear to Walker and his team that a demonic fundamentalist nutjob was at work so arrest the softly spoken Ulster evangelist who leads the New Advent Church! Drag the blighter from his pulpit before the gaze of his shocked congregation!

Given to casting out his followers' demons by locking them up in cellars for days at a time, the softly spoken Ulster evangelist swiftly proved in fact to be an innocent man whose church was possibly allied to Glasgow's Taggart-ite Assembly of the Latter-Day Red Herring. Thankfully, he demonstrated admirable Christian charity by overlooking his rude removal from his church and aiding the police investigation. He near-instantly divined that the murderer was killing folk to create dramatic tableaux that demonstrated the seven frightful signs presaging the end of the world.

Why couldn't Walker and his cohorts, professional crime-solvers all, have worked this out? For one thing, they were too busy almost getting off with one another - or people who looked like former girlfriends - after an evening's drinking, or grieving for their comatose partner, currently in hospital hooked up to a life-support machine.

Or, if they were Walker and his bluff-but-slightly-obtuse partner, DI Terry Hedges, they were fully engaged in performing an engrossing updated Watson-and-Holmes routine, wherein Hedges failed to see what Walker was driving at when he made unexpected utterances of penetrating forensic brilliance framed as gnomic statements (eg "It must have hurt" and "Look at the sand").

Messiah V: part one was jolly convincing. While I have no idea where it's going to go in tonight's part two, I know I'll be there to watch.