Gr 4–6—Readers become time-traveling adventurers in this excellent series. The books are based on the premise that students have passed through a time portal, with six hours to complete a mission such as delivering a pirate map or helping a slave escape. Along the way, they encounter roughly nine people who answer three questions about their work and societal or economic position (for instance, in Greeks, readers come across a temple priestess who explains what she does, sheds light on the festival of Panathenaea, and informs readers that, yes, there are both male and female priests in the temple. The successful completion of the mission sends travelers back to the present, where they find concluding information that places their adventure into historical context. The books are appealingly designed, with a muted photo background with superimposed text boxes for questions and answers and outstanding illustrations that combine colorful living history, historic location, artifact photos, and period art. The stories are interesting enough to keep readers turning pages and will inspire them to learn more. Strong additions.