Grim and unrelenting but well made.

There was a particularly horrible moment in the opening episode of The Mermaids Singing - the first of the Wire In The Blood stories - when a trussed up, naked man was lowered, bottom first, on to a barbed wire-covered metal cone. Happily, the picture was digitally manipulated before matters turned really disgusting.

We were left to imagine the outcome, and it wasn't difficult to guess that this torture was more painful than watching a new ITV comedy series.

This was an unrelentingly grim series, based on books by Val McDermid, that offers nothing in the way of light relief, being one of those dark thrillers featuring a serial killer whose methods of murder are spectacularly unpleasant. The mutilations, which included crucifixion and castration, seem to be based on medieval methods of torture.

Robson Green's clinical psychologist Dr Tony Hill was asked to help by Hermione Norris's equally grim-faced Detective Inspector Carol Jordan. Trouble is, she went behind her superiors's back in recruiting him. "It's Tom Cross - and I am," says her boss on meeting Hill. The trail leads to various gay haunts as the detectives concentrate on finding the killer on the S&M scene which is very different to the M&S scene.

The series is well done, although we're trod this territory before in other grisly TV thrillers. Next week we can look forward to seeing Green himself strung up by his Y-fronts, which is something many people wanted to do after he and Jerome started making records.

The Horizon documentary Freak Wave was just as worrying with the narrator warning: "There's something out at sea terrorising the world's shipping". The something is a 30 metre wall of water that appears out of the blue and batters vessels in the way. "No one knows where it comes from and why it happens," we were told.

Apparently, once a week a ship sinks to the bottom of the ocean. The really worrying thing is that scientists claim that such freak waves are virtually impossible. Tell that to the captain whose ship was hit by one. It was "like banging into a brick wall", he said.

A leading wave mathematician - a somewhat limited job, you feel - started talking about non-linear waves, describing the freak kind as an "unstable, non-linear monster". The size and shape of the waves are what make them deadly, instead of just wet and wild. There are apparently two kinds of waves, just as there are the wrong kind of leaves on the line.