Edinburgh, 1826. Isobel Tait does her best to raise her young son Thomas alone, but yellow fever has left him with a scarred heart. Even a specialist, the renowned Dr. Connall Burnett, can do nothing for him. Isobel decides to make the most the remaining time with her son. Until he goes missing. A chance visit to Dr. Burnett’s collection of specimens elicits a horrifying realization: there, in a small jar among stuffed lizards and misshapen bones, is a new addition. A tiny human heart. The use of stolen bodies by Edinburgh’s medical men is a controversial but open secret. But her own investigation reveals a terrible truth: the doctor’s a proxy killer obsessed with his quest for specimens. And he preys on the vulnerable. With the help of a detective with something to prove, she must gather exact justice and put an end to the doctor's twisted plans—while not getting caught.