learns, agrees to help kill him. However, when the men confront Von Zell in his wolf form, Gabriel is forced to kill him after being bitten when Friedrich hesitates to do the deed. Wounded, Gabriel is sent back to Munich, but slowly discovers that Von Zell has infected him with lycanthropy. In the meantime, Grace conducts research on Ludwig II, and discovers that not only was his health in decline after 1870, he also developed a strong friendship with musical composer Richard Wagner. After receiving an English transcript of Ludwig's diary, she learns that he came into contact with the Black Wolf, who befriended him during talks in Prussia, and infected him during his hunting trip. Seeking to escape his fate, he and Wagner conducted research on werewolves and learnt that if subjected to a specific acoustic frequency, they could be exposed in their true form. While Ludwig had an opera theatre constructed for this purpose, Wagner composed a new opera that could create the frequency needed for their plan to have the Black Wolf killed. When Wagner died, Ludwig received his score sheets and hid them before his arrest on the grounds of insanity. After tracking down Gabriel, Grace discovers that he has been infected with lycanthropy and brings him back to Rittersberg. Comparing notes with him, Grace reveals that a title deed request revealed that Friedrich is the Black Wolf. Gabriel confirms this, after realizing that Von Zell was a beta werewolf that Friedrich created but could not kill without suffering the same fate. Realizing he must be killed, Grace works to find Wagner's missing opera and arranges for it to be performed in Munich, inviting Friedrich to attend alongside Leber. Two months later, Grace works to set up the trap, but secures Gabriel in a prop room for his safety. Confiding in him that she has doubts their plan may work, Gabriel angrily breaks free during her absence, and takes the place of one of the performers. As the opera reaches its climax, both he and Friedrich transform and rush into the basement. Once there, Gabriel swiftly forces Friedrich into a boiler room, whereupon he and Grace trap him in an incinerator, burning him alive. A few days later, Gabriel, now cured, mourns the loss of Friedrich and the man he was, and reconciles with Grace by vowing to have her as his partner on future cases.