The unthinkable happens. Keisha forgets to do her science homework! The morning it's due, she rushes to Locker 37 and the locker gives her a clock. Not just any clock, mind you. It's a time-travel device that sends Keisha back to whatever time of day she wants during that particular school day, which means she can scrape together enough time in between her classes to finish her homework. Still, there's no time to help Carson with his stained shirt or to answer Bryce's gummy bear questions (don't ask). Keisha only has time to make things right--but should she use it for herself or for her friends?