When a patient is electrocuted by a medical therapy device, the manufacturer proves it was tampered with. Who killed her? And what grudge did they hold against her doctor, whose reputation now lies in tatters?

The medical profession's faith in electric shock therapies for treating female nervous conditions is shaken after a patient dies while connected to one such device. Harry Armitage is hired by the doctor arrested for her murder, and he invites Cleo to help him uncover the truth. After all, the doctor is the same one who tried-and failed-to treat Cleo's aunt. As they dig deeper, it becomes apparent the doctor has failed other patients, too, and those patients' loved ones want revenge.

Did that desire for revenge lead to the death of an innocent patient? Or did the victim have enemies of her own? As Cleo and Harry unravel the multi-layered mystery, they realize not everyone is who they seem. Suspects are hiding secrets that, if exposed, could shatter reputations and relationships.

Meanwhile, the manufacturer of a popular but highly addictive medicine has booked the Mayfair Hotel for a major presentation to important clients. As the day of the event looms, Cleo and Harry learn of a plot to sabotage it.

Can they solve the mystery and save the presentation? Or will it be ruined? And will someone get away with murder?