At first, the siblings entertain themselves with an attic full of interesting books and toys, and a pond-like swimming pool surrounded by hummingbirds, brightly colored-butterflies and exotic dragonflies that seem too beautiful for a mortal creature.

Kendra and Seth find out quickly how dangerous this new magical environment is when rules are broken, thrusting them into the middle of a long fight for their lives.

The second book returns to the Sorenson siblings the following year, where a strange new student has infiltrated the school in disguise, causing mischief, and Kendra is the only one who can see the charade.

Seth, with help from the 2 satyrs, Newel and Doren, discovers that someone, or something, has released a plague that transforms beings of light into creatures of darkness.

For the first time, some of the main characters visit another magical preserve, as another hidden artifact must be recovered from Lost Mesa in Arizona.

Things are heating up between the Knights of the Dawn (sworn to protect the earth from magical dangers) and the Society of the Evening Star, who turn to kidnapping Kendra in an attempt to discover secrets.

The race to obtain the 5 magical artifacts continues, and leads the Knights, and the Sorensons, to a deadly dragon Sanctuary called Wyrmroost.

The final book in the series has the Sorenson siblings traveling to different preserves around the earth in the attempt to secure the remaining magical artifacts before the Society gets them.

In the new series, it's been four months since the Demon Prison was closed by Kendra and Seth, with help from the Knights of the Dawn, the Fairy Queen and her subjects, and the Dragons of Wyrmroost.

Agad the wizard had to cut a deal with Celebrant the Just, King of Dragons to gain their assistance, and he was made a co-caretaker of the sanctuary.

Draconic unrest is happening at all the dragon sanctuaries, and Agad was called away to assist at Soaring Cliffs, leaving an opening at Wyrmroost.

Knox is tricked into leaving the Fablehaven keys behind with a goblin, but it causes a huge entrance weakness to Wyrmroost when the barrel disappears stranding everyone there.

Kendra, Seth, and others venture into a cursed castle called Stormguard on the summer solstice, to fight for the legendary Wizenstone in a tournament started by Humbuggle the dwarf.

Kendra is frantic to find her missing brother, but the quest takes her and her companions, including Warren, Tanu, and Vanessa, far from Wyrmroost to Crescent Lagoon—a recently fallen dragon sanctuary made up of many islands and underwater domains.

In addition, it houses the arena for the Titan Games, a series of gladiator-style battles presided over by none other than Humbuggle, the demon who stole Seth's memories.

[3] Brandon Mull wrote a five-book sequel series that picks up right where Keys to the Demon Prison left off.

[5] The New York Times - "Mull's awkward writing sometimes underscores the overfamiliar plot mechanics of the two-children-save-the-world fantasy, but his story offers unexpected twists and entertainingly scary creatures".

[6] Columbia Daily Tribune - "This story is so compelling and so well written you’ll find its magic working on you as well, completely taking over your ability to put the book down, even for a moment.