Tor, Melda, and Engle embark on an adventure miraculous and precarious to save Estrelle from the dreaded Calavera. Following the Night Witch's demise, which led to her cursing (and perhaps blessing) Tor with her prodigious powers, her wide-reaching curses and spells have been broken. The Calavera, a band of fearsome, malicious pirates, now seek the Pirate's Pearl, a powerful orb that grants its possessor the power to control the mighty seas. To halt the Calavera's looming assault on Estrelle, Tor, Melda, and Engle set sail on the Night Witch's ship before the gruesome pirates can reach their beloved village. Aided by newcomer Vesper, a feisty silver-haired waterbreather with her share of secrets, as well as the Book of Seas, Tor and friends gain new friendships, face fearsome creatures and foes, and traverse the ferocious seas in their quest for the Pearl. Aster's brisk, lyrical prose weaves rich, intriguing worldbuilding details and wrinkles into this engrossing series that encompasses tales indebted to Latin American myths. A few slower middle chapters introduce new characters that expand the world's scope; this entry showcases the author's profound strides in maturing her characters, the series' true strength. As Tor grapples with his newfound power and role as the Night Witch's successor, the trio also slowly explores the still-fresh wounds and traumas from their previous adventure. A cliffhanger ending thankfully promises even more adventures. Characters have a range of skin tones. A mightily marvelous sequel. (Fantasy. 8-12) Copyright (c) Kirkus Reviews, used with permission.