A male and female detective chat about the price of fashion boots as they tramp across a desolate landfill site towards an unmarked yellow van.

At least it seems unmarked, but the van's windscreen has 'SAVE ME' scrawled across it in blood, and inside is the corpse of a young student, stung to death by at least 20,000 bees, her hands bound to the steering wheel..

This is in fact the second death in Messiah 4 - The Harrowing, though it happens when the three-part Gothic thriller is just moments old.

"It has a particularly gruesome body count," admits Ken Stott, alias DCI Red Metcalfe. "Messiah 4 will not disappoint."

In fact Ken, 50, says words to that effect every time he films another compellingly ghastly Messiah story but he's been right every time so far, Messiah IV included.

His long-serving DI Duncan Warren (Neil Dudgeon) and new arrival DS Vickie Clarke ( Maxine Peake, looking very different to her tarty neighbour in Shameless) make the gruesome opening discovery but their solution is easy enough - Send for Red.

But it's not only the actors who were given plenty to do to make Messiah 4 chill the blood. The special effects may be small scale but they are effective, as when you see a solitary bee crawl out from the murder victim's nose.

It looks like the worst job in the world for the poor unknown playing the corpse, but in fact no actress was stung or even tickled in the making of the scene:

"It was difficult. They had to make a cast of the actress's face and nose, which takes a lot of time," says producer Peter Norris.

Yet the scene is entirely lifelike, if a corpse can be so described, and there are others even more gruesome to come.

"At one stage we had two prosthetic bodies hanging upside down from a railway bridge," says Norris, and the bodies are naked too. Casting dummies saved someone much suffering:

"We did think we would ask acrobats about the possibility of them hanging upside down, but we were filming those scenes for 12 hours at a time, which was just impossible when people are involved. But the bodies look amazingly believable."

Messiah 4 also stars Helen McCrory as new pathologist Rachel Price and Hugo Speer as her estranged detective husband, who are struggling to cope with the seemingly unconnected suicide of their own university student daughter.

The pathology scenes again leave little to the imagination, with a victim's entire brain being placed stickily onto a weighing scale and blood all over the shop.

Writer Terry Cafolla gained inspiration for all this gore, believe it or not, by taking a trip to the seaside.

Terry, from Armagh in Northern Ireland, is bestknown for his BAFTAnominated script for Holy Cross. His initial idea for his first Messiah script wasn't gelling, so he cycled to Bangorin CountyDownto take the sea air:

"I was sitting on the beach looking out to sea and it just struck me that I had always wanted to use Dante in something I was writing, and this was perfect for Messiah. It was an opportunity to use Dante's structure to look at people's sins and the way they live their lives."

* Messiah 4 - The Harrowing goes out on Sunday, Monday, Tuesday August 28-30, 9pm BBC1