The internship program at the Time Museum is a little unusual. For one thing, kids as young as twelve get to apply for these prestigious summer jobs. And as for the applicant pool . . . well, these kids come from all over history. When Delia finds herself working at the Time Museum, the last thing she expects is to be sent on time-traveling adventures with an unlikely gang of kids from across the eons. From a cave-boy to a girl from the distant future, Delia's team represents nearly all of human history! They're going to need all their skills for the challenge they've got in store . . . defending the Time Museum itself!