During the Second Afghan War, John Watson was shot and also contracted typhus. During this time, Dr. Clifford Smith cared for him.

Many years later, Watson unexpectedly receives an invitation from Dr. Smith to Brixford, Devonshire. His colleague has inherited an old house: Rosie's Hall.

Upon arriving in Brixford, Watson learns that three children have vanished without a trace. He informs his friend Sherlock Holmes about further mysterious incidents at Rosie's Hall.

After extensive investigations, horrific machinations are uncovered, reaching into the highest echelons of the British Empire.