As a child, Henry Knight believed he saw a large monster kill his father on Dartmoor. Twenty years later, Henry is sure that the monster is back and he goes to the brilliant detective Sherlock Holmes for help. Sherlock and John Watson travel to Dartmoor to find out more. Is there really a 'monster of the moors'? And what happens inside Baskerville, the top-secret government centre? Only Sherlock can discover the truth. .