It might be reasonable to assume that this Swedish novel has ridden to its huge success in Europe on the coat-tails of Mankell and Larsson, but this book's hero has much more in common with Voltaire's Candide than Kurt or Lisbeth. Scandi-crime's signature darkness is here dispelled by Allan Karlsson, the eponymous centenarian, who with unlikely sprightliness hops out of the window of his old people's home one afternoon and does a runner  or more of a shuffle. Fast-moving and relentlessly sunny, the novel quickly develops into a romp that takes in all the major events of the 20th century. Like Forrest Gump, Allan is an innocent with the knack of being in the right place at the right time. He has also had a hand in everything from the Russian revolution to Reagan's Star Wars. Meanwhile, Allan's present-day adventure turns into a genial crime-fest as a series of affable rogues join his geriatric conga line. Like Allan, the plot is pleasingly nimble and the book's endearing charm offers a happy alternative to the more familiar Nordic noir.