Black Coffee by Agatha Christie

E-book exclusive extras:1) Christie biographer Charles Osborne's essay on Black Coffee;2) "The Poirots": the complete guide to all the cases of the great Belgian detective.Sir Claud Amory’s formula for a powerful new explosive has been stolen, presumably by a member of his large household. Sir Claud assembles his suspects in the library and locks the door, instructing them that the when the lights go out, the formula must be replaced on the table—and no questions will be asked. But when the lights come on, Sir Claud is dead. Now Hercule Poirot, assisted by Captain Hastings and Inspector Japp, must unravel a tangle of family feuds, old flames, and suspicious foreigners to find the killer and prevent a global catastrophe.