The Whip of Forgetting (The Adventures of the Elderly Sherlock Holmes, Episode 14)

A package without a sender appears one day at Holmes and Watson's door. Five strange objects contained within - a rope, a neck iron, a lump of metal, a withered poppy and a document - point the master detective towards the year 1800. Almost forgotten atrocities suddenly come alive again. Now the only question remains: what does the long-deceased philanthropist Edward Colston have to do with it?