A journey to Whitby heralds the start of a new case for Sherlock Holmes and Dr. Henry Vernier. Their client is in love, but a mysterious letter has warned him of the dangers of the romance. The object of his affection is said to be under a thousand-year-old druidic curse, doomed to take the form of a gigantic snake. Locals speak of a green glow in the woods at night, and a white apparition amongst the trees. Is there sorcery at work, or is a human hand behind the terrors of Diana’s Grove?