Tess de Sousa leaves Miss Ackerbee's orphanage to live with her new guardian in Roedeer Lodge, taking with her a fondness for scientific experimentation, a pet tarantula named Violet, and a device that allows her to travel to parallel universes.

With her passion for scientific experimentation and her pet tarantula Violet, Tess de Sousa is no ordinary orphan. When a stranger shows up at Ackerbee's Home for Lost and Foundlings, claiming to be a distant relative come to adopt her, Tess hopes to find some answers to her mysterious origins. But as she adjusts to her new life at Roedeer Lodge, it becomes clear that Norton F. Cleat knows more about Tess - and the strange device left with her when she was abandoned as a baby - than he's letting on. And when Tess discovers that the Starspinner is the gateway between her world and a parallel world in which war rages, she realizes she may be the key to a terrible plan. A plan she must stop at all costs...