The light of an open doorway beckons through the mist of a London Particular, one of those smothering fogs for which turn-of-the-century London was famous. But in reality-as Sherlock Holmes soon discovers-though the doorway does indeed offer respite from the fog, it also leads to the gruesome remains of a double-murder. Two corpses, a stolen diamond necklace, a Russian connection, and a dandified American writer who pals around with denizens of...