When a sinkhole opens up and swallows one of Bayport?s historic statues, Frank and Joe suspect something?or someone?shady at play. They jump at the chance to investigate; Joe as a member of an urban exploration club, and Frank as photographer for the school paper. But in the thick of their search, the boys stumble upon an entire underground city that?s been abandoned for years. Now the city is home to a cultish band of criminals who plan to take over...

"P.T. and his friend Gloria must solve a mystery at the world's wackiest motel: The Wonderland"--

While on a school trip to the British Arts & Antiquities Museum, John Watson and his friends from the Baker Street Academy get involved in a mystery when the Alpine Star, a famous diamond, is stolen.

After Minty discovers a secret tree with a hollow trunk that holds the secrets of everyone in the neighborhood, Raymond, a new boy drawn to the tree and Minty start watching their neighbors.

Twelve-year-old Steve is investigating a diamond heist but the case suddenly changes when the author of the Bailey Brothers detective novels writes him a letter to say that he fears for his life.

When one of the helmets in Sven the Shouter's private collection is stolen, the micekings find their investigation complicated when the dragons attack.

When upper case letters disappear from Capital City, Question Mark calls on Private I to investigate.

Long-time friends and fellow sleuths Jeff Bunter, Brian Rooney, Mara Lubin, and Kelly Smitts, collectively known as the Goofballs, investigate the disappearance of Thunder the pony in their town of Badger Point.

When someone begins renovating a basketball court at the local park, Zach and Zoe set out to find out who is doing the work.

Jorge teams up with his friends Liza, Ernie, and Carter, the fearsome but friendly chupacabra, to solve the mystery behind an old legend about an evil piñata possessed by a ghost.