There is a paperback edition of Restless - William Boyd's 2006 thriller about a woman who discovers her mother was a Second World War spy - that, on its last page, carries an advert for a chocolate bar. The novel itself begins with an epigraph from Proust. The unlikely conjunction is a symbol of the Scottish writer's position in the UK literary scene, pitched between the mass market and the highbrow. His books fly off the shelves but are also praised in the sort of supplements that never deign to review novels by many a multi-million-selling author. Although Boyd's backlist is diverse, including experiments with forms of biography, and fiction that draws on his boyhood in colonial Africa, the massive commercial success of Restless seems to have persuaded him that his literary destiny lies in penning wartime thrillers. Waiting for Sunrise, his third in six years, suggests that he may already be bored of the genre. A First World War caper set in Austria, Britain and Switzerland, it offers neither the slow-burn mystery of Restless nor the breakneck action of 2009's Ordinary Thunderstorms, a Big Pharma conspiracy yarn in which there's a fatal stabbing and upper-case shouting ("NO! NO! RUN!") within the first 20 pages. The story here takes a while to get going; Boyd doesn't hit caps lock until more than halfway through ("BOOM!"). It begins in 1913. A young English actor named Lysander Rief visits Vienna - "the city of facial hair", Boyd writes - to undergo a course of psychoanalysis. A shameful incident from his teenage years has left him with an embarrassing condition that he would like to cure before he marries Blanche, his actress fiancée back in London. But things don't go to plan. He embarks on a four-month affair with a sculptor, Hettie Bull, who then gets him arrested when she makes a grave (and unfounded) allegation. The British Embassy pays his hefty bail and sanctions his flight from Austria in disguise as an Italian double-bass player (his professional skills come in handy on a crowded railway platform). But the embassy's assistance means that Lysander can't refuse when it later recruits him to spy on the Germans. Let's be clear: Waiting for Sunrise is a mess. The problem is not the ludicrous plot - Eric Ambler built fine novels on still less believable foundations - so much as the half-hearted execution. We are prepared to accept any amount of implausibility in the name of excitement - it is a thriller, after all - but what is harder to accept is how little Boyd bothers to dress up the haphazard encounters on which his tale depends. Time and again the hero's eye is "caught" by someone whom the narrative requires him to meet: the crush of a drinks party serves the purpose more than once ("Lysander turned to see Miss Bull standing there"). Someone appears at a vital moment "as if she had suddenly materialised". The frank lack of artifice has the paradoxical effect of making events feel wholly contrived and thus free from tension. It's as if the author is pulling plot elements out of a hat, rather than (as with the switchback time frame in Restless) working through a clever plan designed to keep us on our toes. Boyd's epigraph this time comes from Hemingway rather than Proust, so it's ironic that so much in the book is told rather than shown. Retrospective narration doesn't have to be undramatic, but it tends not to sit well in a narrative that lives or dies on the level of suspense it generates. A favourite storytelling method here is for Lysander to recount events from the comfort of a bar: "He sipped his whisky and lit a cigarette, his mind turning inevitably towards Hettie", and "He ordered a dozen oysters and a pint of hock and allowed his thoughts to return pleasingly to Blanche.