Jack and Annie are ready for their next fantasy adventure in the bestselling middle-grade series—the Magic Tree House!"Beware of Vikings!"Warns Morgan. Then Jack and Annie are whisked back to ancient Ireland. They land on a cliff on a misty island. How will they find the story they are looking for? It will take a Viking invasion, the help of a jolly monk, and a lot of courage for Jack and Annie to succeed in Viking Ships at Sunrise.