Amid a mountain of rain-soaked donations to the Ohnita Harbor Public Library rummage sale, Gabriela Domenici finds a small box that contains an odd-looking cross. When the carved center turns out to be ivory and a clue links the cross to Catherine of Siena, a medieval saint, Gabriela turns to her expertise as an authenticator of historic documents to lead the quest to discover the truth about this mysterious object. But the cross isn't the only secret in town: beloved Friends of the Library volunteer Ellyn Turkin is found floating in the harbor and an antiques dealer, Derby Collins, is murdered on the library lawn. As Gabriela races to solve the mystery of the cross, she becomes disillusioned by an infatuation, then finds the start of what may be true love. All the while, she must stay one step ahead of the danger that slowly encircles her.