Three fifth grade "detectives" - Millie, Mike and Marta - as they solve the never-ending mysteries of the fictional, small, Arkansas town of Mulberry Springs.
It's time to dig up the time capsule buried fifty years ago at Mulberry Springs Elementary. But when the time capsule isn't where it should be, the Mystery League jumps into action and uncovers the key to the community's past!
A show and tell güiro is missing. The Mystery League is on the case learning about families and cultures along the way. / Mockingbird Creek is overrun with litter. Can the detectives find the source of the trash and clean it up?
3. Case of the Mystery Mash /Case of the Robot Teacher
Lunchroom Larry guards his mystery recipe closely. When the detectives try to crack the recipe, they learn about the journey food takes to our plates. / Is Spencer Lewis' teacher a robot? The detectives work as a team to find the truth.
When the city library gets a boatload of books from a mysterious donor, the detectives set out to track down The Helpful Hero. / A food critic is visiting Chuck's Wagon Restaurant. The detectives search for the critic's secret identity.
5. Crop Circle Mystery Part 1/crop Circle Mystery Part 2
The Harvest Festival is here, and strange circles appear in local cornfields. Wild rumors of extraterrestrials jeopardize the upcoming festival. The Mystery League works to learn the truth and save the Harvest Festival.
6. Mystery of Matlock's Millions/Egg-Citing Adventure
When they learn about a local legend of buried treasure, the detectives make a map to find the gold. / Millie travels back in time, to find the school abuzz with the discovery of a dinosaur egg, but Millie is determined to get proof.
When the Mystery League's investigation points to Marta's new camera, she is forced to choose between what she wants and what is right. / Visiting a local museum, Marta and Terrell take a journey through state history and national symbols.
As mayor for the day, Millie learns that being a leader often means asking for help. / Millie works to convince her friends to take a school vote seriously, when everyone is more interested in the identity of Sammy the Sloth!
9. The Mcgillicuddy Solution Part 1/the Mcgillicuddy Solution Part 2
The detectives uncover the identity of the author of The Dancing Detective. Their final investigation leads them to someone they never suspected. / Old Man McGillicuddy helps the detectives track down the key to the city!
