Cover of Dark MatterDark Matter by Juli Zeh, translated by Christine Lo (Harvill Secker, £12.99)

Drawing extensively on recent physics Juli Zeh has put together a complex and emotionally moving piece of crime fiction. Can you commit a murder in one world, but not have done so in another? Could you escape from the world where you did to the world where you didn't? These are the kind of intriguing questions the narrative poses.

Set in Southern Germany and Switzerland, the story explores the intense relationship between two physicists, whose early close friendship at university has developed into something altogether more prickly as their careers, and beliefs, have gone in different ways. Oskar is a high-powered international scientific star working on the CERN project, single and totally committed to his research; Sebastian a physics lecturer in Freiburg, happily married with a wife and young son, who have become at least as important to him as his work. Oskar comes to dinner with the family once a month, sessions at which Sebastian's belief in Many-Worlds Theory is causing increasingly bitter arguments with his exasperated friend. They clash over the subject on a television discussion programme, during which Oskar mercilessly mocks Sebastian's theories, aired recently in the national magazine Der Speigel under the headline “Everything that is possible happens”. For Oskar this is intellectually beneath contempt, little more than “doublethink”. Shortly afterwards, Sebastian's son is kidnapped from his car at a service station, while being driven to a summer camp. A mobile phone call when Sebastian discovers the car gone informs him that in order to get his son back he must kill a man, an acquaintance of his wife, and must on no account involve the police. So begins a chilling series of events.

The murder which follows is shocking, even to such a desensitised age as our own, and Sebastian's sheer horror at being drawn into a world which can include such actions, even if it is to save his son from harm, is very convincingly portrayed. Despite appearing to tell us all we need to know to identify the perpetrator of the kidnapping (most readers will probably work this out fairly quickly), the ending still has surprises in store, courtesy of some deft handling of the interaction between scientific theory, metaphysics and human psychology. The dialogue can sound somewhat stilted on occasion (an effect of translation from the German perhaps?), and the author sometimes strives rather too self-consciously for a poetic note, but from the murder onwards this grows into a compulsive read. And there are some neat touches of humour dropped in at the expense of the characters' pretensions; most of them do seem to inhabit their own private worlds.

The book's most striking character is Schilf , the experienced detective brought in to help break the case. Suffering from a severe medical condition, Schilf also has to cope with an ex-pupil of his, Rita Skura, who is nominally in charge of the murder case and less than receptive to her teacher's rather Zen-like methods of crime solving. The story gradually comes to focus mainly on Schilf as he struggles to cope with both his illness and the tangled threads of the crime, and he turns into a genuinely tragic hero in the process.

The Many-Worlds Theory is used adroitly by the author, and it is all the more effective in not being pushed too far into the realm of fantasy – except for dreams, including day-dreams, for which it has a clear affinity. The notion that there are several, possibly an infinite, number of ways the narrative can develop – even if we have a strong inkling of where it has to end – is ingenious and deftly handled, reinforcing and deepening the overall sense of eerie suspense.