The Big Four: An emaciated stranger approaches Hercule Poirot, shouts a warning about "the big four" and drops dead. Who knew Poirot's inquiry into the man's odd behavior would lead to an underground laboratory, an insane asylum, and rumors of a secret weapon? Murder in Mesopotamia: The Queen of Mystery has come to Harper Collins! Agatha Christie, the acknowledged mistress of suspense creator of indomitable sleuth Miss Marple, meticulous Belgian detective Hercule Poirot, and so many other unforgettable characters brings her entire oeuvre of ingenious whodunits, locked room mysteries, and perplexing puzzles to Harper Paperbacks. Suspicious events at a Middle Eastern archaeological excavation site intrigue the great Poirot as he investigates Murder in Mesopotamia.