Joe and his friend Skip are enjoying the thrill of the Big Dip, a famous rollercoaster, until they learn the old man in front of them has been shot. The old man mutters with his dying breath something about getting a Margaret Rose to the police. Joe leaves the crime scene to get on with his life. But someone is desperate for the Margaret Rose and thinks Joe has it. When his sister is kidnapped, Joe is in a race against time to solve the puzzle.
Zack Freedman has complete control and feels a sense of calm on the high wire. If only he could say the same about the rest of his life. His fellow youth circus performer and roommate, Cubby, hates him, and his aunt dumps a yappy, excitable dog on him. When a necklace is stolen during a circus performance and the victim of the theft threatens to shut down the circus, Zack is desperate to solve the mystery so he can keep his place on the wire.
Clay would much rather work as a lifeguard at the beach than at Safari Splash, the new water park in town. He's certain the summer will drag along, despite his position at the Boa, the park's fastest slide. The summer job starts to get interesting when he learns that someone has been wandering the park in a lynx costume, scaring the staff. When forty thousand dollars is stolen from the till, and his friends are under suspicion for the theft, boring is starting to look good. But Clay is certain that the mask and the thefts are connected, and he's determined to solve the crime.
While volunteering at the local zoo, Robyn, Nick and Trevor learn that grizzly bears are being poached and their gall bladders removed for use in alternative medicine. Always ready to solve a mystery, the kids set out to find the poachers. Bear is not only big game, they learn, but big money to poachers. The stakes are high and the suspects many, as the kids head into their most dangerous adventure yet.
Safira doesn't believe in ghosts, but the girl in her cabin at camp was not a living person, so what was she? Her friend Trinity is convinced Safira's seen a ghost and sets out to discover who the ghost girl is. Safira is too busy dealing with her family to help solve the mystery. Safira has never gotten along with her sister, Mya, and now that Mya's pending marriage dominates the family, there seems to be no hope for friendship between them. But when Trinity discovers the death of a girl named Myra, Safira starts to wonder if the ghost-girl has an important message about her own sister.
Dylan and his friends snowball cars for entertainment on the weekend. When they don't get enough reaction from passing cars, they put rocks in the middle of their snowballs. Their first attack with the loaded snowballs causes a car crash. His friends flee, but Dylan goes to the scene of the accident to make sure the driver is okay. He runs off when he knows help is on the way. Dylan is sighted, and rather than being punished, he is lauded as a hero. As his lies pile up, so does the hype about his heroics, and along with it, Dylan's guilt.
Dorf is all about skateboarding and so far that's worked out fine. But now that he's in a new city, the terrain has changed. He's no longer free to skateboard where he wishes, school is more difficult, and his passion for skateboarding garners him the nickname and reputation of a freak. With daring stunts he gains the grudging respect of local troublemakers, but he needs to tap into another kind of courage to effect real change.
Sam's grandfather vanished from his life the day Sam's father was buried. Now, ten years later, Grandpa Max wants to make amends. He sends letters that lead Sam on a scavenger hunt. Sam follows his grandfather's bizarre instructions though he's still not ready to forgive. To alleviate his anger at his grandfather, Sam turns to his favorite stress release: climbing onto roofs and leaving his tag, a spray painted symbol for Aquarius. When he gets caught by an elderly couple, Sam learns a valuable lesson about forgiveness. He's ready to forgive his grandfather, but is he too late?
When Trevor, Nick and Robyn visit the Royal Tyrrell Museum, Robyn is inspired to raise funds for a dinosaur dig that will close soon if it doesn't find funding. The kids are caught up in another mystery when a chain of suspicious events, including the disappearance of important fossils and a fraudulent discovery at the dig, leads them to wonder what's going on. Is the new visiting scientist behind the fraud, or did Robyn's enthusiasm to save the dig lead her astray?
Trevor, Nick and Robyn are ready to solve another mystery. When bobsledder Josh Gantz is accused of deliberately injuring a fellow competitor, he runs the risk of being thrown out of the sport -- right before the World Cup. Courtney Gantz asks Trevor, Nick and Robyn to help clear her brother's name. Can they find out who framed Josh? What is the meaning of the strange coded messages they keep finding around Olympic Park? Who eats orange bananas, anyway? The kids must unearth the clues in a race against time, before Josh's championship dreams end up on ice.
Angus and his best buddy, Shahid, share a love of science and their robot, Gordon. But recently, the artistic Ella Eckles has had a peculiar effect on Angus. When a stink bomb at the school provides a chance for him to talk to her, he claims to share her interest in reading facial expressions and declares his ambition to become a crime-solving mentalist. He impresses Ella by identifying the stink bomber, but fails to mention he witnessed a scrawny kid setting off the bomb. When Ella's treasured sketchbook is stolen, she asks Angus to find the thief. Shahid thinks Angus should confess that he's not a mentalist, but Angus is certain he can learn to read people and recover Ella's sketchbook. He asks Shahid to help him investigate the suspects: Gaga Girl; the art teacher, Mr. Wilder; and finally, "scrawny kid." Equipped with rearview sunglasses and an informant who lurks in the washroom, the duo bungles their way through a series of encounters that alarm Shahid and provide Angus with some unfamiliar exercise.