Stranded in Victorian England, Kat tries to locate the inventor who can restore her time machine and send her home.

Having traveled in her time machine to the court of Kublai Khan, Kat comes to the aid of a Mongolian princess who is facing a fearful future.

Laurel sets off into the gloomy Great Forest to track a new friend-- who may have stolen the woodfairies' most precious possession.

Sailor York and the daring recruits of Explorer Academy uncover an elusive animal-smuggling ring in the first electrifying book in this new five-book series. Soon after Cruz, Sailor, Emmett, and Lani return for their second year at Explorer Academy, their sense of calm is shattered when Sailor’s older sister goes missing. Amidst incredible expeditions to far-flung destinations and competitive classes, Sailor bravely steps into the lead to discover how her sister’s sudden disappearance may be linked to an illegal and deadly animal-trafficking ring. Despite winning the prestigious North Star Award and being surrounded by close friends and teachers who she has traveled the world with, Sailor’s never felt less sure of herself. As the recruits face puzzling obstacles and try to follow complex clues, Sailor realizes there’s only one thing that could save her sister in time: revealing her own deepest secret.

Kat and Aunt Jessie visit Renaissance Italy with their time machine, where Kat and her friend, a would-be artist, inadvertently become involved in a plot to steal notebooks from Leonardo da Vinci.