By Pierce, Tamora 

When sixteen-year-old Beka becomes "Puppy" to a pair of "Dogs," as the Provost's Guards are called, she uses her police training, natural abilities, and a touch of magic to help them solve the case of a murdered baby in Tortall's Lower City.

This is Book 1 of The Legend of Beka Cooper and is a "prequel" story about an ancestor of many of this author's other books' characters.

By Scott, Michael Dylan 

While working at pleasant but mundane summer jobs in San Francisco, fifteen-year-old twins, Sophie and Josh, suddenly find themselves caught up in the deadly, centuries-old struggle between rival alchemists, Nicholas Flamel and John Dee, over the possession of an ancient and powerful book holding the secret formulas for alchemy and everlasting life.

Book 1 of The Secrets of the Immortal Nicholas Flamel

By Pratchett, Terry  A talking cat, intelligent rats, and a strange boy cooperate in a Pied Piper scam until they try to con the wrong town and are confronted by a deadly evil rat king. Set in the Discworld universe.

By Enthoven, Sam 

When his best friend, Charlie, is possessed by an ancient demon who takes over his body via a writhing black tattoo, fourteen-year-old Jack, accompanied by a girl with superhuman powers, battles all over London and even into Hell to save him.

By Richards, Justin 

Fifteen-year-old Matt and his new friend Robin search the globe to retrieve an ancient code--rumored to have brought down the ancient civilization of Atlantis--from the hands of a madman who is bent on destroying the modern world. Cool mix of modern technology and ancient mystical magic.

By Patterson, James 

Fifteen-year-old Daniel has followed in his parents' footsteps as the Alien Hunter, exterminating beings on The List of Alien Outlaws on Terra Firma, but when he faces his first of the top ten outlaws, the very existence Earth and another planet are at stake.

Sequel: Daniel X: Watch the Skies

By Chima, Cinda Williams 

Relates the intertwining fates of former street gang leader Han Alister and headstrong Princess Raisa, as Han takes possession of an amulet that once belonged to an evil wizard and Raisa uncovers a conspiracy in the Grey Wolf Court.

By Yancey, Richard 

Through a series of dangerous and violent misadventures, teenage loser Alfred Kropp rescues King Arthur's legendary sword Excalibur from the forces of evil.