Kelsey can't resist collecting secrets in her spy notebook just like her hero, Harriet the Spy. When she learns Leo has been hiding something from the group, she writes his secret in her notebook as well. But when the notebook goes missing, everything she’s collected about classmates, friends, and family could be revealed to the world! After receiving a ransom note, Kelsey tries to solve the mystery on her own. But she soon realizes she needs help from everyone in the CCSC to rescue the notebook, help a homesick 130-year-old Aldabra tortoise, and unmask a thief.

VOYA Perfect Tens 2015 No one at school knows that Kelsy, Becca, and Leo are secretly friends. They have nothing in common—until they rescue three kittens and form a club to help animals through volunteering, spying, and solving mysteries. Kelsey helps catch a runaway zorse (horse + zebra) with the help of the nicest and most popular girl in school, Becca. The two are walking home when they happen upon a litter of kittens trapped in a dumpster and Leo is the only person around who can help get them out. The three unlikely friends decide to work together to help solve animal crimes with their secret club.

Catch the first three Curious Cat Spy Club titles in one adorable collection! No one at school knows that Kelsey, Becca, and Leo are secretly friends. They have nothing in common—until they rescue three kittens and form a club to help animals through volunteering, spying, and solving mysteries. Includes The Curious Cat Spy Club, The Mystery of the Zorse's Mask, and Kelsey the Spy.

When Kelsey and her friends find an abandoned pug puppy, it looks like another case for the Curious Cat Spy Club. But shortly thereafter, Kelsey's mother goes missing—possibly in the line of duty as an Animal Control officer—and it's up to the CCSC to discover what happened. As they search for Kelsey's mom, they start to wonder if her disappearance is somehow linked to the puppy they found. The fifth book in the Curious Cat Spy Club series is filled with twists and turns and, of course, tons of animal adventures!

When a mysterious stranger claims to own Becca's beloved zorse, Zed, the Curious Cat Spy Club fears he might be responsible for abusing Zed in the past. Kelsey, Becca, and Leo are determined to uncover the truth before they have to give him away. But when a daring rescue attempt puts Kelsey in danger, does the CCSC have enough spy skills to save her, or are they in over their heads?

Kelsey's dad has a new job and that means a new house—on the same property as a castle! Kelsey, Becca, and Leo can’t wait to explore, but what they find might lead to their most intricate case yet. How are an abandoned tree house, a wad of cash, a missing heirloom, and a mysterious creature roaming the grounds all connected? The Curious Cat Spy Club is determined to find out!