When his beloved caretaker Mrs. Phillips tells him she's leaving, William is devastated. Not even her farewell gift of a model medieval castle helps him feel better—though he has to admit it’s fascinating. From the working drawbridge and portcullis to the fully-furnished rooms, it's perfect in every detail. It almost seems magical.

And when William looks at the silver knight, the tiny figure comes to life in his hand—and tells him a tale of a wicked sorcerer, a vicious dragon, and a kingdom in need of a hero. Hoping the castle's magic will help him find a way to make his friend stay, William embarks on a daring quest with Sir Simon, the Silver Knight—but he will have to face his own doubts and regrets if he's going to succeed.