Members of the Critter Club are all excited about their summer plans until Liz learns that, instead of taking an art class, she will have to be in summer school to improve her math skills, but a fun teacher, a classroom pet, support from her friends, and advice from her brother might get her through.

While her friends in the Critter Club babysit frogs, second-grader Marion enters a fashion design contest.

As her friends in the Critter Club animal shelter care for colorful aquarium fish, second-grader Liz and her family spend a long weekend at the beach, where Liz rescues a baby octopus and competes with an unfriendly young neighbor in a sand castle contest.

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.

"Ellie has always wanted to go to wedding, and her hopes finally come true when her cousin asks her to be a flower girl at her wedding. Then the Critter Club gets the cutest guest Ellie has ever seen: a little French bulldog. Ellie works hard to find a home for the puppy, but she's worried she won't be able to. Suddenly she has an idea that will guarantee that the puppy lives happily ever after!"-- Provided by publisher.

Valentine's Day is near, and to raise money for a charity called Puppy Love, Ellie persuades the other Critter Club girls to join her in selling and delivering singing telegrams.

During Spring Break, mystery lover Amy looks for clues to the disappearance of wealthy Ms. Sullivan's Saint Bernard puppy.

"When Amy meets the owner of a brand-new puppy at her mom's vet clinic, she agrees to help the woman train her new pet. Amy does such a great job, she starts getting calls from more puppy owners! Things go great for a while, but soon, Amy is in way over her head. She can't say no to a puppy in need and has taken on way too many clients! Amy barely has time for school or her friends in between all the puppies. Can she dig herself out of this hole before...

Unless Amy and her friends in the Critter Club can come up with an alternative plan, new stores are going to be built on the town's park, endangering the lives of the plants and animals living there.

Liz and her friends are spending a fall weekend at the cabin at Marigold Lake, planning to bake pies and enjoy nature, but Lizzie forgets to put sugar in her berry pie--a mistake which proves fortuitous when she needs a lot of berries to feed a migrating goose who has fallen behind his flock.