Messiah V - The Rapture (BBC1, 9pm) City of Vice (C4, 9pm)

JOSEPH Walker, the new DCI in the latest Messiah thriller, comes equipped with something that no detective can do without - a nasty case of the flashbacks. This is a disease that particularly affects TV cops. Whenever the going gets tough, the flashing starts and we are offered tantalising glimpses of something awful in their past.

Marc Warren's Walker takes over from Ken Stott's equally troubled detective. He's first seen somewhere in the Middle East with a beautiful woman. This is another requisite of TV policemen, who appear to be magnets for desirable females. It must be the smell of the crime scene about them that attract women.

Anyway, Walker's lady friend gets out of the car and straight into a suicide bombing explosion. As she looks vaguely recognisable - she was mad Maya from Coronation Street, I suddenly remembered - you can be certain that's not the last we've seen of her.

Back in this country, Walker is occupied with another series of murders and must work out the connection.

At the first crime scene they find an entire family - mother, father and children - sitting at the table with their hands tied in front of them. They're all dead.

They look like they're praying and, true to Messiah form, the killer appears to be working his way through some religious prophecy.

The second death is of a woman hanging from the ceiling dressed in a man's suit.

These are relatively mild deaths compared to some previous gruesome killings in Messiah.

The death of a girl in an alley ups the gore factor.

"What's that?", asks someone pointing to a red object, like a pepper, lying by the bloody body.

"That's her heart," comes the reply.

All this has something to do with a court case about a father accused of raping his daughter. And what's the significance of the messages written in sand left at the crime scenes?

Connoisseurs of such thrillers won't have too much difficulty guessing the identity of a killer attempting to orchestrate nothing less than the end of the world. That's pretty ambitious, even by the standards of Messiah's killers.

Like Stott before him, Warren feels obliged to adopt the appearance of a miserable git.

Who can blame him with those flashbacks constantly interrupting his thoughts?

None of the killings in Messiash is half as unpleasant as the sight of Dennis Rickman from EastEnders wearing a dress and being taken from behind by a man friend in City Of Vice.

The second in the Georgian London detective stories finds Henry Fielding, magistrate and author of Tom Jones, reading the dirty bits of Fanny Hill (presumably by gaslight).

He founded the capital's first police force, the Bow Street Runners, who this week are to be found along Sodomites Walk, a sort of gay version of the Lambeth Walk.

The body of a vicar is found stabbed in his church. He was being blackmailed over the flaw in his character. He was a bit of a macaroni which, we learn, is a term applied to homosexuals.

I don't like to think what macaroni cheese involves.

The investigation takes Fielding and his blind brother John on a tour of London's molly houses where men would gather to drink, dance and commit unnatural acts like drink tea out of their saucers.

Some of them dressed as women, like Princess Seraphina and Thomas Deacon (that's Nigel Harman, a long way from his shirtless hunk days on EastEnders).

He's a little too friendly with one of Fielding's team, Daniel Carne, a bit of a macaroni dish he knows as Jamaican Mary.

The pair get married in a parody of a wedding that ends with Deacon giving birth to a wooden baby.

Sir Charles Cavenidsh is getting ratty at the slow progress of the investigation, telling Fielding: "I will have a hanging or you will lose the funds" - threatening to take away the money given to establish the Bow Street Runners.

The novelist is too busy with Fanny to get on with the investigation. He's reading the unexpurgated version, he says looking up from the pages, "to see what I might uncover".

Just watch out if he asks his wife to get him a plate of macaroni cheese.