Black Coffee

In the spring of 1934 Poirot is summoned to Surrey by England's most prominent physicist, Sir Claud Amory. Amory fears that someone in his household is attempting to steal his latest discovery, a formula critical to England's defence. Poirot, with Captain Hastings at his side, rushes to Surrey, but arrives too late: Amory has died, his formula is missing and anyone in his country house, full of relatives and guests, could have been responsible.