Years ago, the owner of a grand estate confronted an evil entity called the Shade that lived inside a large mirror. In the present, the Master Detective receives word that her friend Eleanor Codington — the original owner's granddaughter — has gone missing while attempting to reopen the estate. With the Queen's permission, she goes to investigate despite knowing the Shade still dwells there. What she finds inside is a mirror reality full of enslaved servants, sealed rooms, and a blood ritual that is the only way to stop the Shade for good — but only if the right person performs it.