Sherlock: Season 2, Episode 2

2 - 2: The Hounds of Baskerville

A Hound from Hell. A terrified young man. Sherlock's most famous case. But is a monster really stalking Dartmoor? Something terrible has happened to Henry Knight. Sherlock and John investigate the truth about the monstrous creature which apparently killed their client's father. But what seems like fantasy in Baker Street is a very different prospect in the ultra-secret army base that looms over Dartmoor...