Allie and Shoo Spywell is just regular kids-well, sort of. It's just that their dad is an archaeologist, and their mother is a mystery writer. The Spywell kids always seem to get a few more history lessons than they would like. While left on their own to explore the Detroit Historical Museum, Allie and Shoo soon meet strange characters. Shoo meets a boy in red tennis shoes who becomes even more mysterious and stranger as the afternoon wears on. Allie, meanwhile, is taken by the woeful stories of a weeping woman who is dressed in an ancient French gown and claims to be the wife of Antoine de la Mothe Cadillac, Detroit's founder. Allie learns the true accounts and mysterious happenings of old Detroit as she tries to warn Shoo that his new friend is not a friend at all, but holds the secrets of Madame Cadillac and her husband. Shoo is the only one to save them but will he be able to rescue them before they are permanently trapped in Detroit's past?
The boy in the red shoes is actually based on the "Red Devil" that is found throughout the writings of Cadillac, and not an imaginary character created by Panagopoulos.