When the Sweet Sixteen party plans of a local rich girl are overshadowed by pranksters who key her expensive car and post a video of the act on the Internet, Frank and Joe resolve to identify the culprits.
While attending an amusement park under the new ownership of their friend Daisy, Joe and Frank investigate the disappearance of a patron who was last seen riding a hit attraction, an event that has threatened Daisy's family's livelihood.
Scoffing at an urban legend about a cannibalistic madman during a field trip to Black Bear Mountain, the Hardy brothers are on the case when their teacher goes missing, stranding their class in the wilderness with no way to call for help.
When Joe and Frank Hardy stop a group of ranch hands from stealing the Welch family's prize horse, they are invited to help drive cattle back to the Welch ranch, where they encounter dangerous acts of sabotage.
While assisting a conservation mission at the Bayport Aquarium, Frank and Joe travel to the Florida Keys, where their studies about the local shark population are complicated by a missing paddle boarder.
When Frank and Joe Hardy go to Kids Day at the King Arthur Faire in Bayport, they run into Chet Morton. Chet won the Junior Joust competition and now has a ticket to a real jousting competition until the ticket goes missing. It is up to the Hardy boys to find the missing ticket and see if there is a rogue knight on the loose.
When their summer is marked by more claims of Sasquatch sightings than usual, an ensuing media blitz prompts Frank and Joe to investigate the truth, an effort that is complicated when some of their friends are attacked by a furry creature.