Italy, June 1300. In a disused church on the outskirts of Florence, the master craftsman, Ambrogio, is found murdered at the foot of an unfinished mosaic. A young Dante Alighieri, (future author of The Divine Comedy) the recently elected Prior to the City of Florence, is called upon to investigate. He learns that the church is being transformed into a university at the behest of the new Pope, Bonifacius VIII. Closer inspection reveals catacombs beneath the floor, populated with beggars and thieves, who speak of witchcraft and satanic rituals practised above. Meanwhile, the Church, on learning of Dante's involvement, begins to show an unusual interest in Ambrogio's fate. But Dante has one further lead; Ambrogio belonged to a society of learned men, The Third Heaven. Dante hears they are in Florence for the founding of the new university, and believes that if he can infiltrate this group he may uncover the significance of Ambrogio's work. Perhaps the key to the murder is the mosaic itself. Leoni sets this clever thriller in a city on edge, nervously recovering from civil war. Medieval Florence is portrayed with stunning clarity; a city on the cusp of the Renaissance, in which new learning - in the guise of Dante - takes on the dark forces of old. The Third Heaven Conspiracy is a breathtaking whodunnit.