Ben returns home to the royal city of Quadrivium expecting a hero's welcome. Instead, he finds the city in turmoil. The king has been found dead in suspicious circumstances, clearing the way for someone to rule the kingdom through the infant prince. Ben immediately suspects his old enemy, the pale man. Or could it be the vainglorious Cardinal Bolt, who shows an excessive interest in the Book of Prophecies? The race for the heir is on when the prince is discovered to be missing.
Accompanied by his old friends Murgatroyd and Tobias, Ben sets out on a perilous journey across the uncharted waters of the Sylver Sea to the Abbey of the Ancients, where he believes the prince is being held. Hindered by sea monsters and savage storms, and helped by unexpected allies, Ben battles to be the first to reach the prince - but an unexpected surprise is waiting for him at his destination.