The Alchemist's Apprentice — Dave Duncan

To the legendary clairvoyant Maestro Nostradamus, the future is forever in motion. But for young swordsman Alfeo Zeno, his apprentice and protector, the present is hard enough to contend with. His days are spent poring over astrology charts and making calculations, his nights learning arcane magic or transcribing Nostradamus's nebulous prophecies. Until one night, when the Council of Ten arrives to take the seer into custody.

It seems that a high-ranking friend of the prince died under mysterious circumstances after Nostradamus cast his horoscope, warning of danger-and rumors are swirling that the mystic poisoned the victim to enhance his own reputation. Alfeo is stunned when his master refuses to flee. Instead, Nostradamus charges Alfeo with the task of clearing his name. Now, Alfeo must unravel a web of magic and murder if he is to have any future of his own.