On a spring morning in London's Strand, the Speaker of the House of Commons is accidentally killed by a van unloading oranges and lemons for the annual St. Clement Danes festival. It's an absurd way to die, but the government is more interested in investigating the Speaker's state of mind just prior to his accident. The task is given to the Peculiar Crimes Unit -- the only problem being that the unit no longer exists. Its Chief, Raymond Land, is tending his daffodils on the Isle of Wight and senior detectives Arthur Bryant and John May are out of commission; May is undergoing surgery for a bullet wound and Bryant has been missing for a month. What's more, the old unit in King's Cross is being turned into a vegetarian tapas bar. Against impossible odds, the team is reassembled and once again what should have been a simple case becomes a lunatic farrago involving arson, suicide, magicians, academics and a race to catch a killer with a master plan involving London churches.