Sherlock Holmes acquires a new client when a beautiful young woman, Isabel Stone, faints on the steps of his Baker Street rooms.

She has come to beg his assistance in reclaiming some priceless jewels kept from her by her tyrannical stepfather, Captain Grimbold Pratt. But shortly after agreeing to take her case, Captain Pratt comes to Baker Street, not quite so tyrannical as Isabel would have them believe.

Holmes and his cousin, Dr Henry Vernier, must unravel a tense family mystery dating back to the Indian Mutiny, where neither of them is sure who to believe…