Steel Magic (The Magic Sequence Book 1)

Sara Lowry and her brothers Greg and Eric are transported back to the time of King Arthur after discovering a medieval castle near their uncle's Hudson Valley estate. They must recover three lost talismans—Arthur's sword Excalibur, Merlin's ring, and the horn of Huon, Warden of the West—and return them to their rightful owners, or remain trapped in the distant past. The adventure begins when Sara wins a picnic basket at the Firemen's Strawberry Festival. While their parents are in Japan, the three siblings stay with their uncle and become fascinated by the manor's history. During a search for a legendary lost lake, they are enveloped by a gray mist that transports them to King Arthur's time. There they learn their mission is crucial: they must save Avalon, the only place standing between the Powers of Darkness and the mortal realm, and find their way home.