Why do we like reading novels about murder?

Isn't it a bit weird, and shouldn't we worry about it? Is it normal to imagine one human killing another: the gun going off, the knife going in, the poison doing its work in the bloodstream? In other words, should murder really be fun?

In Painting Death, the third novel to feature the art dealer, criminal and anti-hero Morris Duckworth, Tim Parks attempts to tackle some of these questions while also making us feel rather uncomfortable in the process, which helps makes his point. Painting Death is a book that questions the idea of murder as entertainment while also making murder entertaining. It's supposed to make us squirm and it does.

At one point, Duckworth, who is attempting to stage an art exhibition on the theme of murder, tackles the question of death-as-art directly and asserts that artists have always enjoyed revelling in brutality. "We love looking at it," he says. "We always have. In a way, we've all killed a million times, in our heads … These things happen. Art requires them."

This is typical of Duckworth, an unpleasant character who generally has his smugness turned up to its maximum setting. At the start of the novel, he is about to receive honorary citizenship in Verona's town hall even though he should be residing in Verona's penitentiary but he delights in his secret: the fact that he has killed and killed again and nobody around him knows it. "His knowledge went deeper than theirs," he says, "inches of steel deeper."

If you think some of this sounds familiar, of course it does. Painting Death is the story of a well-to-do, murderous aesthete living on the continent and getting away with his crimes 50 years after Patricia Highsmith first wrote the story of a well-to-do, murderous aesthete living on the continent and getting away with his crimes.

In fact, so strong is the similarity between Duckworth and Highsmith's character Tom Ripley that it frequently feels as if Ripley is butting into the narrative and reminding us why his novels are so wonderful and why Parks's fail to reach the same level. The trick to Highsmith was that her style was cool and detached and beautiful which made you want to like Ripley; Parks's style on the other hand is talky and descriptive and revelatory, which leads you to dislike Duckworth intensely. It was always a strange relief when Ripley got away with his crimes; when Duckworth does so, it is galling.

The novel does have ideas that are likely to linger, the strongest of which is the fact that one of Duckworth's previous victims can talk to him through a painting (unless of course Duckworth is mad and is imagining the whole thing). As he ponders his crimes, and his feelings, you realise that a weird, inconsistent morality has grown up around his murdering ways. This is why criminals have their codes: even if they kill other people, they need to feel that there are rules.

For example, Duckworth is a vegetarian and at one point wonders why. "It's not the actual killing," he says, "but the fact that they don't even allow these animals a life in the first place. Oh, if I knew they'd been killed in a fair fight, I'd eat 'em up gristle and bone."

Who knows if that is horrible or understandable - it's certainly not the kind of morality that's easy to get your head around, which is probably Parks's point. There is none of the clean morality of traditional detective fiction here: everyone is rather nasty and venal and corrupt and selfish. It is a whodunnit in which everyone has dunnit to some extent.

The problem is that the actual whodunnit element, which centres on the death of the director of the gallery where the exhibition is being held, is not as interesting or as clever as it should be. The character of Duckworth could have made up for this: he certainly has the potential to explore some interesting ideas about the way we think about murder and the fact that some of us - all of us? - have thought, or said, "I could kill him" or "I wish he was dead".

But Duckworth never manages to do the wonderfully disturbing thing that Ripley does: he never makes you want him to win, you never feel charmed by him, which means all you can do is sit and listen to him talk about his vile crimes and put up with him glowing with satisfaction that he's got away with them again. "A mellow old age lay before him," he thinks at one point, and, sadly, it probably does.