The Dragons of Ordinary Farm — Tad Williams

Tyler and Lucinda have to spend summer vacation with their ancient uncle Gideon, a farmer. They think they're in for six weeks of cows, sheep, horses, and pigs. But when they arrive in deserted Standard Valley, California, they discover that Ordinary Farm is, well, no ordinary farm.
The bellowing in the barn comes not from a cow but from a dragon. The thundering herd in the valley? Unicorns. Uncle Gideon's sprawling farmhouse never looks the same twice. Plus, there's a flying monkey, a demon squirrel, and a barnload of unlikely farmhands with strange accents and even stranger powers.
At first, the whole place seems like a crazy adventure. But when darker secrets begin to surface and Uncle Gideon and his fabulous creatures are threatened, Lucinda and Tyler have to pull together to take action. Will two ordinary kids be able to save the dragons, the farm -- and themselves?
Expert storytellers Tad Williams and Deborah Beale take readers on an extraordinary adventure in their first book about Ordinary Farm.