As a child, Giovanna Visconti learned the arts of bloodletting and elixir brewing from her father with an intent to simply support his work, not take it over. But when he falls ill from the pestilence that's been ravaging Venice for months, she reluctantly dons the beaked mask of the plague doctor. Vowing to protect her father however she can, Giovanna hides him away and sees her first patient--the handsome, but alarmingly feverish Matteo Barozzi. Although she successfully treats this son of a high-ranking official, in a careless moment Giovanna fails to properly conceal her identity. The only reason she isn't tossed into a dank jail cell is thanks to the young man's honor and feelings of indebtedness.

The association between the charming aristocrat and the clever commoner should end there, but when Giovanna's dearest friend goes missing right after her betrothal to the Doge's son and amid strange reports of nighttime attacks, violent commotions, and inexplicable behaviors in the community, the only person Giovanna can turn to for help is Matteo. Together, they must carefully navigate Venice's increasingly deadly canals to uncover a sect peddling false cures and a smuggling plot involving the highest levels of government or risk the entire Republic falling victim to something even worse than the plague: the risen dead.