The evidence can disappear. Witnesses can die. Decades can pass. But murder has a long memory.In Bristol, Louisa Dunne was murdered in her own home in 1967. Her killer escaped justice for almost sixty years-until evidence preserved by detectives finally revealed his identity.Inside a hollow tree in wartime Worcestershire, children discovered the remains of an unidentified woman. Soon a question began appearing in graffiti: Who put Bella in the Wych Elm? More than eighty years later, nobody knows.In North Wales, schoolteacher Caroline Evans set out on a familiar Saturday-night journey to visit her mother. She never arrived.At a lonely bungalow on the Sussex coast, the disappearance of Emily Kaye led police to one of the most extraordinary murder investigations of the 1920s.And when Bella Wright was found shot dead beside a country road in 1919, suspicion fell upon the mysterious stranger who had been riding alongside her on a green bicycle.Detective Files #4 examines five remarkable British cases spanning more than a century of detection-from crimes solved by persistence and advances in forensic science to mysteries that have resisted every attempt to explain them.The evidence is examined without embellishment. The theories are separated from the facts. And behind every famous mystery is returned the person who matters most: the victim.Five cases. Some solved. Some still hauntingly open. All unforgettable.