Twelve-year-old Ben Brown runs away from the circus with his dog (and best friend) Sancho to seek out his missing father. He stumbles into the lives of young sisters Bab and Betty Moss who live with their mother in a quiet, tidy house. Ben's juggling skills, Sancho's trick of spelling his name with letter blocks, and the duo's other tricks of the trade charm the small family while Bab and Betty's whimsical antics and their mother's steady goodness and understanding are a welcome refuge for Ben, who constantly worries about his father.

Ben begins working for a nearby farm and moves in with the Mosses' next-door neighbors--Miss Celia and her teenage brother, Thornton--whose garden is full of lilacs. As much as Ben cares for his new companions, he chafes at the slow pace of his new life, used to the excitement of the circus. And when his beloved Sancho goes missing and Ben gets accused of theft, he starts to wonder if he can ever truly fit in his new life.