Legend has it there's a treasure in the Islands. Everyone's after it, including Jem Fitzgerald and his explorer uncle, Finn, the Islanders, and pirates. Even the infamous crew known as the Lost Souls-rumoured to be ghosts-has set their spyglasses on it. But only Uncle Finn holds the map to the treasure-until he's kidnapped by pirates and made to walk the plank, after quickly handing off the precious map to Jem. Before the pirates can send Jem overboard, he's rescued by the Lost Souls. It's the fright of his life-until he discovers that the so-called ghosts are actually children! Sailing the Island waters, the Lost Souls, led by the daring young captain Scarlet McCray, offer haven and adventure to children in need. But can Scarlet convince Jem to give up the map? Can she quiet the mutinous rumblings of her crew? Or will the reign of the Lost Souls end with her?