When a demure, engaged librarian, who led a double life as a prostitute in a local saloon, is found strangled, Anna Fulford, still on the run from the Black Hand, helps Murdoch in his murder investigation.

When another prostitute from the Devil's den is strangled, Murdoch discovers they both sang in the same choir, and there is no shortage of suspects.

Detective Murdoch investigates the sudden death of bicycle racer Joe Fenton. Murdoch was himself a participant in the race trying out his newfangled gear shifting device but Fenton was the favorite having won several recent races. Fenton's manager, Chippy Blackburn, was seen giving him a potion and they suspect he may be may be fixing races. Dr. Grace however is having considerable difficulty finding a cause of death and with Dr. Ogden's assistance performs her first brain bisection. It leads her to believe he suffered a cerebral aneurysm leading to a brain hemorrhage. The discovery of an injection mark in Fenton's right arm leads to a different conclusion however. Meanwhile, Julia prepares to sell Darcy Garland's house but finds that his younger brother Leslie living is living there.