The first and most important thing to say about The Drowned Detective is that it’s a very good novel and (which is not always the same thing) a pleasure to read. After that, it gets more complicated.

The book defies tidy categorisation. Set in a nameless eastern European country, it opens in the literary territory of the crime thriller, with private investigators on the trail of a government minister on the way to visit his rubber-clad mistress. One of them, the narrator Jonathan, is English. He’s furiously jealous of his employee Frank, a hunk who has had a fling with Sarah, Jonathan’s archaeologist wife.

In another case, the parents of a missing girl have retained Jonathan to search for their daughter, Petra. Here the story lurches into different territory, for information on Petra’s whereabouts comes from Gertrude, an elderly psychic with a marvellous line in malapropisms and an ailing Pomeranian named Phoebe; Gertrude, a self-confessed charlatan, believes that Petra is ‘in a small room she cannot leave’ and pinpoints the girl’s approximate location by burning a hole in a map of the city with the heat radiating from her hand.

Added to this are the occasional trappings of a political thriller, for the city is convulsed by unrest. Summer heat warps the passions. Protesters in rainbow balaclavas and carrying boomboxes meet with violence from police in black balaclavas. Putin’s tanks are waiting on the other side of the border.

A girl attempts to kill herself one night by jumping from a bridge guarded by blind stone dragons into the polluted river that divides the city In a sequence that has the dreamlike logic of an Edgar Allan Poe story, Jonathan dives in and rescues her. He takes her home to her apartment, where she tells him she is a cellist at the opera house.

At the heart of the novel, however, is a doomed, double love story, a shifting triangle between the cellist and Jonathan and Sarah — whose marriage is disintegrating, despite their regular visits to a psychotherapist. The process is watched by their daughter Jenny, whose comments to her imaginary friends form a sort of Greek chorus. Music plays an important part for both the living and dead – particularly Bach’s Cello Suite No. 2.

Neil Jordan’s films include The Crying Game and The End of the Affair. (This would make a good film too.) He is an expert at narrative on the page as well as the screen. The Drowned Detective is a seductive book. It wins you over gradually and stealthily. Its impact is cumulative rather than sudden, and only with hindsight do you realise how cunningly it is constructed and how carefully it is patterned.

Gertrude, the psychic, is perhaps the closest the story comes to a reality checkpoint. If the book has a moral, it’s she who points it out: ‘The dead can cause more trouble than the living. In fact they invariably do.’