While enjoying the Christmas season, Nan and Sarah, along with Dr. Watson and his wife Mary, are called to investigate when missing women reappear and their experiences while gone have driven them mad.

1888. After a disasterous Ripper investigation, Holmes sinks into a deep depression. Watson can do nothing to help his friend, but an encoded letter from the French singer, Emmeline La Victoire, rekindles the detective's interest. The singer's illegitimate son, Emil, who is 10, has disappeared, and may have been kidnapped. As Holmes and Watson travel to Paris, they discover that Emil's father, the Earl of Pellingham and a famous art collector...