Three nuns are murdered in the attic of a Boston convent.
There are no witnesses.
No shell casings.
The only things missing are their rosaries.

Days later, a Boston medium claims her spirit guide has identified the killer: a broken priest with an antique revolver. A single newspaper column turns that claim into a city-wide witch hunt.

Harvard “pope whisperer” Cal Donovan and former Vatican power broker Elisabetta Celestino step into the city’s séance rooms to test the story. What they uncover is a trail of antique ballistics, buried secrets, and a generations-old vendetta that reaches back to Arthur Conan Doyle and the birth of modern Spiritualism.

To save an innocent man, Cal and Elisabetta must decide whether they are chasing a brilliant fraud who hides behind the dead, or facing something far more unsettling: the dead really are answering back.