A picaresque novel about Allan Karlsson, who decided that he did not want to attend his hundredth birthday party at the old-age home where he was staying so he decided to leave, with no particular plan for what he was going to do. He has various improbable adventures, and the story is told with a series of flashbacks to his life story. He was a self-taught explosives expert, and as such had played a minor but significant part in various world events, learning several languages along the way and earning the gratitude of several powerful politicians.

I read it mainly because I had seen a film based on the book which I had enjoyed, and from what I could remember of it the film seemed to adhere quite closely r=to the book.