On June 8, 1870, Charles Dickens concluded a full-day’s work on his latest novel and set down his pen. He died the next day, leaving The Mystery of Edwin Drood a mystery indeed. MASTERPIECE CLASSIC uses clues left by the author himself, together with inspired guesswork, to solve this famous literary puzzle. Adapted and completed by Gwyneth Hughes (Miss Austen Regrets), The Mystery of Edwin Drood stars Matthew Rhys (Brothers & Sisters), Tamzin Merchant (The Tudors), and Julia MacKenzie (Miss Marple), and airs Sunday, April 15, at 9 p.m.