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The 15th adventure in this hugely successful series. Follow Jack and Annie across the world and through time!

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A tale of high waves and high adventure for Jack and Annie when the tree house lands in the sea off the coast of Ireland. Things get dangerous when Viking ships approach!

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"Beautifully written, full of suspense and well-researched" Waterstones Books Quarterly 20080301

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Mary Pope Osborne is the author of over forty books for young people. She was the president of the Author´s Guild, the leading organization for professional writers in the US, for two years and has won many awards for her books. She lives in New York with her husband, Will, and their dog, Bailey, who sleeps on top of Mary´s desk every day while she writes.

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