When Marion finally gets the chance to babysit her little sister, she finds that the task is harder than she expected, especially when she gets called to the Critter Club to help with a stray cat and must bring Gabby along.
After winning the lead role in a play, acing a spelling test, and finding money, second-grader Ellie wonders if the Critter Club animal shelter's newest animal--a little pink pig--is bringing her good luck.
When a broken ankle forces Marion to withdraw from the horse show, she finds a way to stay active by helping her friends at the Critter Club animal shelter find homes for a litter of kittens.
Liz is horrified to learn that she has to take summer school, but with some time management and help from her friends, she learns that she can still have a fun summer anyway.
Zach's mom has a new patient a giant dog named Millie who has been helping her owner train for a marathon. Millie's knees can't handle all that running and now she needs an expensive operation! Time for the kids in the Pet Rescue Club to help! Together they find a way to help Millie.