Quintessence (paperback) by David Walton :: Cover Art by Kekai Kotaki

Christopher Sinclair is an alchemist who cares only about one thing: quintessence, a substance he believes will grant magical powers and immortality. And he has a ship. Fleeing an inquisition, physician Stephen Parris follows Sinclair to an island that perches upon the farthest horizon, bringing his daughter Catherine with him.