Teenage detectives Frank and Joe Hardy investigate a supposedly haunted house reported to be the hangout of criminals.

Blue bells will be singing horses! This strange message, attached to the leg of a wounded homing pigeon, involves Nancy Drew in a dangerous mission. Somewhere an elderly woman is being held prisoner in a mansion, and  Nancy is determined to find and free her. Meanwhile, the young detective’s close friend, Helen, begs her to solve a second mystery. Helen’s grandparents, the Cornings, are frightened by a sinister wheel of blue fire...

"Drop case or else danger for you and your family." This warning addressed to Fenton Hardy not only alarms the famous investigator and his detective sons, but also puzzles them, because Mr. Hardy is working on more than one case. Which one prompted the threat? When more ominous warnings follow, Frank and Joe suspect there is a link between the counterfeiting case they are investigating and a secret case their father cannot discuss since it involves...

An anonymous diary is a mystery with handwriting that is difficult to decipher. It is filled with technical drawings and chemical formulas. Was the destructive explosion an accident or an act of revenge?

Dink and his friends unearth the mysterious truth behind the envelopes incorrectly delivered to his house.

America's Sherlock Holmes in sneakers continues his war on crime in ten more cases, the solutions to which are found in the back of the book.

Nothing is what it seems and there's always more than one side to the story as a group of strangers trapped in an inn slowly reveal their secrets in this new standalone mystery set in the world of the best-selling Greenglass House.

When their game of neighborhood spying takes a dark turn one night, pre-teen sleuths Sophie Young and Grace Yang find themselves caught in a dangerous cat-and-mouse game with their bizarre guidance counselor, who may be hiding something sinister.

After a family tragedy, Jacob feels compelled to explore an abandoned orphanage on an island off the coast of Wales, discovering disturbing facts about the children who were kept there.