Everything in Mallory McDonald's life is changing! Fourth grade is over and summer is off to a shaky start. The Winstons are moving from Wish Pond Road to a bigger house across town, so Mallory's best friends, Mary Ann and Joey, won't be living next door anymore. And her friend Chloe Jennifer will be gone for the whole summer. On top of all this, Mallory's cat, Cheeseburger, suddenly gets sick!

How will Mallory deal with all these changes? Will the vet help Cheeseburger get well? And will Mallory find new ways to have fun this summer?