Chased by a secret order, thirteen-year-old Wade Kaplan (plus step-brother, cousin, and cousin’s best friend) traverses the globe searching for parts of an age-old astrolabe that doubles as a time machine—although in the first book (The Forbidden Stone), an actual spanning of time is limited. There is a second book (The Serpent’s Curse) and a collection of novellas (The Copernicus Archives).