There are thousands of parallel universes out there, and it's the Agents' job to make sure you never see them. Three new trainees have just joined the Agents' ranks, including a surprise recruit, fourth grader Boo. The problem is that Boo is young and small, even for her age. But Boo will learn that being small and quiet has great advantages, too.

There are thousands of parallel universes out there, and it's the Agents' job to make sure you never see them. Three new trainees have just joined the Agents' ranks, including a surprise recruit, fourth grader Boo. The problem is that Boo is young and small, even for her age-not to mention a scaredy-cat. But Boo will learn that being small and quiet has great advantages, too!