Curse of the Forgotten City (Emblem Island, #2)

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.