On Emblem Island all are born knowing their fate. Their lifelines show the course of their life and an emblem dictates how they will spend it. Twelve-year-old Tor Luna was born with a leadership emblem, just like his mother. But he hates his mark and is determined to choose a different path for himself. So, on the annual New Year's Eve celebration, where Emblemites throw their wishes into a bonfire in the hopes of having them granted, Tor wishes for a different power. The next morning Tor wakes up to discover a new marking on his skin...the symbol of a curse that has shortened his lifeline, giving him only a week before an untimely death. There is only one way to break the curse, and it requires a trip to the notorious Night Witch. With only his village's terrifying, ancient stories as a guide, and his two friends Engle and Melda by his side, Tor must travel across unpredictable Emblem Island, filled with wicked creatures he only knows through myths, in a race against his dwindling lifeline.

After unwillingly inheriting all of the Night Witch’s abilities, Tor Luna is the most powerful person on Emblem Island—though he doesn’t want power at all. Fresh from their last adventure, a girl from a forgotten underwater city named Vesper, with the same water-breathing emblem as Tor, washes ashore—with a warning. Pirates are coming to attack Emblem Island. Using the Night Witch’s enchanted ship, Tor, Melda, Engle, and Vesper set off on a dangerous journey to find the only thing that can save Emblem Island from the cursed Calavera pirates—a pearl, with the power to control the sea. But just like their first, this quest won’t be easy. In a race against time, they will face giant sea creatures, explore coastal cities teeming with assassins, and make alliances with conniving pirates—but knowing who to trust could prove to be the most dangerous part of all.