When Samantha "Sam" Archer and her friends in the nature club arrive in Yellowstone Park on a school trip, they find that the park superintendent's son may have been kidnapped.
When Franklin Middle School's sixth grade class visits the public library, Sam, Egg, Gum, and Cat investigate scratching noises and a book series that is always on hold but never checked out.
While on a school field trip to New Orleans, sixth-grader Catalina Duran becomes wrapped up in a mystery when someone attempts to sabotage their trip and Catalina must uncover the culprit.
On a science class trip to the aquarium, Catalina "Cat" Duran and her friends discover that two of the seals have been drugged and investigate to discover the person responsible.
When Catalina "Cat" Duran and her friends in the History Club arrive at Mount Rushmore on a school trip they find that someone is playing dangerous tricks and trying to drive people away from the park.