MacGill-Callahan (When Solomon Was King, 1995, etc.) explores the Celtic world in this story starring an ingenious Irish maiden, Oonagh, who answers a pirate king's riddles to win back her betrothed, an expert weaver named Conal. Expert agriculturalist Oonagh will wed Conal on May Day; he's happy, she's happy. Then the warriors of Malcolm, pirate king of the islands, kidnap Conal and every other person skilled with needle and loom. Oonagh, rushing to rescue Conal, comes across Ethne, a southern princess pining for the love of Malcolm's son, Aidan, whom she thinks she's lost because she failed to solve a series of riddles. Undeterred, Oonagh rows to the pirate's isle, issues her challenge, answers the riddles, and escapes with Aidan, Conal, and the pirates' kidnapped slaves by inventing sails--""a new word for a new idea."" As the book swashbuckles to its not unforeseen ecstatic end, all loose ends are knotted up as neatly as expert-weaver Conal would have wished: There's a double wedding, and Malcolm is laughed out of countenance, becoming ""the proudest grandfather in all Ireland."" In Manchess's first picture book, painterly oils answer the demands of this story, with fierce posturing on all sides. Oonagh's swagger and riddle-answering will appeal to young readers, even if the motives behind all the heroism isn't particularly germane to most in the picture-book set.