The Tears of the Furies — Christopher Golden; Thomas E. Sniegoski

Behind the facade of a stately Boston brownstone, humanity's last defenses are being marshaled. Called to action by the enigmatic, brilliant man known only as Mr. Doyle, they hail from all planes of existence and are born from an array of supernatural and otherworldly backgrounds and bloodlines...

When word comes to Doyle of a series of inexplicable deaths in and around Athens--men and women turned from living flesh into cold stone he dispatches the Menagerie to Athens to investigate. But he soon follows when he realizes that he has sent them into a far greater danger than he imagined. For the queen of the Gorgons herself has risen. To defeat her, the group will have to descend into Hell itself...and some may not return.