A bored Sherlock decides to take on the case of Henry Knight, who claims to have seen the footprint of a gigantic hound in the woods. He also claims that 20 years before he had seen his father mauled to death by the creature. Holmes assumes that the source of the creature is the nearly Baskerville military research facility. Using his brother Mycroft's identity card, he and Watson gain access to the facility though his ruse is quickly found out. His faith in his abilities is shaken to the core when he too sees the creature, something that genuinely frightens him.