One hundred and fifty years ago, the first dinosaurs were cloned. Soon after, they replaced humans at the top of the food chain. The only way to survive was to move into underground compounds.... Five years ago, Sky Mundy's father vanished from North Compound without a trace. Now she has just stumbled on a clue that not only suggests his disappearance is just the tip of an even larger mystery but also points directly to the surface. To find her dad - and possibly even save the world - Sky and her best friend, Shawn, must break out of their underground home and venture topside.

Regan Fitz and Elliot Mason have been enemies since they started training to become Glitchers - people who travel through time to preserve important historical events. But everything changes when they find a letter from Regan’s future self, warning them about an impending disaster that threatens them and everyone they know.

Hank, Emerson, and their friends have returned to Camp Outlier for another summer of fun and shenanigans. Hank won’t let his RISK (Recurring Incident of the Strange Kind) factor of inconvenient invisibility stop him from having the best summer ever, even when it starts mysteriously turning people and objects around him invisible too. But between his invisibility and an internet celebrity joining their cabin, camp clown Hank is struggling to maintain his spotlight.

When a mysterious little free library (guarded by a large orange cat) appears overnight in the small town of Martinville, eleven-year-old Evan plucks two weathered books from its shelves, never suspecting that his life is about to change. Evan and his best friend Rafe quickly discover a link between one of the old books and a long-ago event that none of the grown-ups want to talk about. The two boys start asking questions whose answers will transform not only their own futures, but the town itself.

Sara Martinez is a hacker. She recently broke into the New York City foster care system to expose her foster parents as cheats and lawbreakers. However, instead of being hailed as a hero, Sara finds herself facing years in a juvenile detention facility and banned from using computers for the same stretch of time. Enter Mother, a British spy who not only gets Sara released from jail but also offers her a chance to make a home for herself within a secret MI5 agency. Operating out of a base in Scotland, the City Spies are five kids from various parts of the world.