Abby can hardly believe her luck. Spring break is just around the corner and her teacher has asked her to pet-sit Mr. Nibbles, the class hamster. But there's one problem. The apartment building Abby lives in has a dumb rule: No Pets Allowed. Should she tell her mom about Mr. Nibbles? Should she try to sneak him into the apartment? Even when Abby finally gets home, nothing turns out the way she expects. For one thing, Mr. Nibbles likes Tess better than her. Then Rachel arrives and things go from bad to worse. Fortunately for Abby, the last surprise is the best one of all.