An urgent telegram from Inspector Forrester calls Sherlock Holmes and Dr. John H. Watson to Reigate, Surrey, to assist his friends at Leidstone Manor: two sibling writers whose manuscripts have been stolen. The siblings, Aubrey and Kate, have received a dire threat: renounce their inheritance and leave for America at once, never to see their beloved dying Uncle Hugh again, or the thief will give Sir Hugh the manuscripts and expose truths that could ruin their lives. As Holmes and Watson search for evidence, an illicit love affair, concealed identities, family secrets, and a mysterious benefactor muddy the waters; there are others who have as much to lose as the siblings. With lives hanging in the balance, Holmes and Watson race to stop a murderer at the end of the hidden lane.