When Benny Alden sees a set of keys that were lost at the library, he follows clues to find the owner.

"When Nancy finds an old desk at a tag sale, she soon finds out that someone left behind a key. Nancy and Bree set out to unlock the secret of the silver key in the hopes of finding some treasure along the way."-- Page [4] of cover.

Diego is under the spell of the wizard Maldred who wants to control the Naga, an enormous dragon that lives deep within the Earth, and plans to use Diego to steal the two keys necessary for that purpose; the first key is guarded by Argent, the silver dragon, and Jean his dragon master, so Drake, Bo, Carlos, and their dragons travel to Gallia to try and stop the theft and break the spell on Diego.

In their third trip through the enchanted library, Cleo and Evan land in "The Werewolf's Curse" where Evan is promptly bitten by a werewolf, and the two need to find the cure--and the next key--before the full moon rises and Evan becomes stuck in this horror story forever.

Clara is searching for the special key to unlock a box from her late mother. Inside that box is a priceless item that her mother left for her. During her godfather's yearly holiday party, Clara almost gets the key but it disappears. She embarks on a quest into a mysterious world which has four different realms: a snowflakes realm, flowers realm, sweets realm, and the challenging realm where the key is. As she undertakes her journey she meets different...

In their second trip through the enchanted library, the new key lands Cleo and Evan in the middle of a spy story, where their impossible mission is to stop a traitor who calls himself Viper--and they find themselves working with the replacement librarian, Ms. Crowley, whose exact role in their adventures is becoming increasingly mysterious.

This time Cleo, Evan, and Ms. Crowley (who, it turns out, is the missing Ms. Hilliard's sister) find themselves in a confusing fantasy book, caught up in a war with wizards, elves, trolls, and the mighty Golden Dragon--and while they manage to find their missing librarian, their quest does not end there.

Having taken the silver key, the evil wizard Maldred is after the gold key, which is protected by the Gold Dragon and her Dragon Master, Darma, but by the time Drake and Rori get there, Eko and her Thunder Dragon have seized the gold key--so together the three dragon masters, follow her through the portal to Maldred's tower, but without their dragons will they be able to stop Maldred and his deluded helper, or even save themselves?