Rain by Karen Duve, translated by Anthea Bell

"How could he have done it? You didn't move to the GDR, you moved away from it," asks Karen Duve of Leon Ulbricht, a failed poet and the protagonist of her first novel, Rain. It's only a few months since Leon left Hamburg for the one-street village of Priesnitz in the East, and he is fast approaching a nervous breakdown.

He should be cheerful. He is married to the beautiful Martina Voss, and has a lucrative deal to write the biography of feared Reeperbahn pimp Benno Pfitzner, and a dream house in which to do it. Built on marshland, however, Leon and Martina's idyllic hovel is sinking – and dragging them down with it. It has been raining for what seems like forever. And we are immersed in a sludgy world of misfits and deviants, a swamp "garlanded by frogspawn" and "rich, rank, wet jungle smells of growth and decay".

Acclaimed for Rain, for short fiction and a second novel recently published in Germany, Duve is a fine observer. When handling Martina's eating disorder, the discovery of decomposed bodies or how the local shop owner fancies himself with a touch of nail varnish and a dress, the author maintains a tone equally unsentimental and moving, and often wickedly comic. Take the moment when we first learn of Martina's compulsion to binge and vomit: "Half a nut got stuck in her nostril in the process. It hurt, but if she stopped now to extract the nut she would have to begin all over again, building up the nausea from scratch."

Leon makes some headway on the book, despite spending days fixing the plumbing and dealing with a death-defying colony of slugs. But Pfitzner, now the editor of terror, is not so sure about his work and demands a series of rewrites before their relationship meets its brutal end. All the while, Leon and Martina's closest neighbours, the Schlei sisters, busy themselves like Lorelei figures, pouring ever more mystery over the obscure landscape.

Which brings us back to the question: why did Leon move to the East? Aside from his namesake being Walter Ulbricht, the politician who had the Berlin Wall built, the sole explanation seems to be that the East offered Duve a savage fictional void begging to be filled – at least from the West's point of view. That's disappointing when you consider what the country has been through since the Wall fell in 1989. Duve's fellow "Wessi" author, Michael Kumpfmüller, whose Adventures of a Bed Salesman is also set in the former East, is rather more eager to get to grips with the mixed bag that reunification represents.

There remains a lack of definitive German reunification novels. This wouldn't be such a problem if Rain stood for itself. But Duve loses the tension; two-thirds of the way in, the plot takes an unconvincing turn. While the rain does eventually stop, the novel never really ends.