he has been called the empress) of England's Golden Age of mystery fiction. And in true Golden Age fashion, her oeuvre opens with, yes, a country-house party between the two world wars - servants bustling, gin flowing, the gentlemen in dinner jackets, the ladies all slink and smolder. Even more delicious: The host, Sir Hubert Handesley, has invented a new and especially exciting version of that beloved parlor entertainment, The Murder Game.