Lorenzo’s Daggers begins in Florence in the year 1478 with an approaching conspiracy to murder Lorenzo de Medici. As the conspirators gather, we are suddenly taken to the present day on a windswept, snowy Block Island morning. It is the final day of classes before the winter break at the prestigious Block Island Academy High School, and history teacher Prester John is lecturing his class on the Italian Renaissance. During the lecture, twin daggers once belonging to Lorenzo de Medici are being displayed. An angry young student, Kirk Renzo, grabs one of the daggers and runs away, his footprints leading through the freshly fallen snow to a 500-year-old tree. Prester gives chase, but at the tree the footprints end. The boy and the dagger have vanished. Suspicion over the boy’s disappearance falls hard upon Prester John. Ostracized by his friends and colleagues, Prester’s life is turned upside down until he meets a physicist who theorizes that the boy has slipped into a parallel universe and been transported to 15th Century Italy. Indeed, young Kirk has finally found his niche, his knowledge of the modern world serving to propel him to the level of Prince in Renaissance Florence. Prester travels back in time to find his lost student, but there are unseen dangers around every turn with political rivalries boiling over. Enlisting the aid of a fellow time traveler from 1940 named Halifax, as well as Michelangelo and Da Vinci, Prester tries to convince Kirk to return home. Kirk refuses, wishing to retain the power he has accrued, and he places Prester under arrest. When King Louis of France threatens to attack Florence, however, Kirk realizes the error of his ways. Unfortunately, he and Prester have missed their window of opportunity to return home. Kirk and Prester are taken prisoner by King Louis’ army. Just as all appears lost, Prester and Kirk are saved from the hangman’s noose through the creative intervention of Da Vinci and the woman who would become known as Mona Lisa. Returning triumphantly to Florence, Prester realizes that he has miscalculated and that it is still possible for them to return home. Racing to the prescribed spot, the pair is transported back to where they started on Block Island. In an epilogue, a young French boy comes across notebooks left by the now deceased Halifax. The boy’s name is Michel de Nostradamus.