While visiting a ranch near Yellowstone National Park with his parents, Summer, and her parents, Teddy Fitzroy investigates the disappearances of bison and an irreplaceable necklace.

The local police prove unhelpful when a 500-pound dinosaur skull vanishes from a secret excavation on Sage's family's ranch, so Teddy and his friends conduct their own investigation.

Twelve-year-old Teddy Fitzroy is the prime suspect when FunJungle's newly-acquired koala goes missing, thanks to a prank staged by middle school bully Vance Jessup.

While visiting his girlfriend Summer in Malibu, Teddy stumbles upon two mysteries involving a blown up whale explosion and a string of beach sand thefts, but his investigation is sidetracked by a rumor that his girlfriend is dating a celebrity, leading him to question their relationship.

For once, operations at the enormous zoo/theme park appear to be running smoothly (except for the occasional herring-related mishap in the penguin exhibit) and Teddy Fitzroy is finally able to give detective work a rest. But then a local lion is accused of killing a famous dog--and the dog's owner, an inflammatory radio host, goes on a crusade to have the cat declared a nuisance so it can be hunted. However, there's evidence that the lion might have...

In 2041 on Moon Base Alpha, thirteen-year-old Dash must solve the mystery of how Lars was poisoned before the base loses oxygen, forcing the colonists to return to Earth.