The unnamed spy of The IPCRESS File uncovers a secret buried deep in a Nazi U-Boat A sunken U-Boat has lain undisturbed on the Atlantic ocean floor since the Second World War - until now. Inside its rusting hull, among the corpses of top-rank Nazis, lie secrets people will kill to obtain. The sequel to Len Deighton's game-changing debut The IPCRESS File, Horse Under Water sees its nameless, laconic narrator sent from fogbound London to the Algarve, where he must dive through layers of deceit in a place rotten with betrayals.