Fablehaven: Keys to the Demon Prison (2010)

Fablehaven: Keys to the Demon Prison is the fifth and final installment in the Fablehaven series by Brandon Mull.

Plot

Kendra, Seth, and the Knights of the Dawn continue to take the last possible steps to safeguard the keys and locks placed on Zzyzx. Graulas asks Seth to recover the Sands of Sanctity to ease his suffering as he dies and Seth agrees.

Kendra, Seth, and the Knights of the Dawn go to Obsidian Waste, the secret preserve in Australia, to get the Translocater, a magical teleportation device and one of the five keys to Zzyzx. They are welcomed by the caretaker Laura and twins Camira and Berrigan. Laura quickly kills Camira because she was plotting behind their backs, and reveals that many members of the Society of the Evening Star are waiting to ambush them. Several members of the Society appear and the group quickly flees to the Obsidian Vault where the Translocater is hidden. Laura sacrificed herself in order to stall the society from capturing the group and one of the team members Vincent died during the trials. After a series of trials they get the artifact, only for the Society to capture Seth, Mara, and Berrigan, while Trask, Tanu, Elise, and Kendra escape with the Translocater.

After being captured, Seth is summoned to talk with the Sphinx. The Sphinx reveals that they are in Living Mirage, the fifth secret preserve, that he is the caretaker of. He also tells Seth that he is a shadow charmer and that he has the Font of Immortality and the Oculus, the last artifacts. The Sphinx imprisons Seth in the dungeon where Seth reunites with Maddox and befriends Bracken, another prisoner. Seth learns that Bracken is a unicorn with no horn and is stuck in human form due to him giving up his third horn to make the Font of Immortality. Then he takes Seth to Nagi Luna, a demoness who mentored the Sphinx. When Seth and Nagi Luna telepathically communicate, Nagi Luna reveals that she secretly wishes to betray the Sphinx and open Zzyzx on her terms. She offers to give Seth power and that they will betray the Sphinx together but Seth refuses.

Back in Fablehaven, Vanessa reveals her secret: Grandpa and Grandma Larsen are alive and are undercover spies for the Knights of Dawn at Living Mirage. Kendra and the rest plan a rescue mission with the Translocater, but they are captured by the Sphinx in the attempt, thus giving the Society four artifacts. Kendra is summoned to talk to the Sphinx where he reveals his master plan. While Kendra is talking with the Sphinx, a mysterious figure slips Seth a sack containing the Translocater and the Sands of Sanctity. With the Translocater, Seth escapes to Fablehaven and uses the Sands to heal Graulas, but Graulas betrays him and takes the Translocater and the Sands, revealing that Nagi Luna was the one who had the artifacts slipped to Seth. Graulas quickly overthrows the treaty and claims the Chronometer, killing Coulter in the process. He then teleports to Living Mirage and takes over the Society of the Evening Star.

Just before, Kendra is taken to the dungeon and meets Bracken. They both are broken out by Warren with the help of the Sphinx and the three, Kendra, Warren, and Bracken, head to the local fairy shrine where the Fairy Queen sends Raxtus the dragon to help them escape over the preserve's wall.

Meanwhile, Seth follows Coulter's last words to a secret message left by Patton Burgess. In the message, Patton suggests some truly desperate ideas to prepare to oppose the demon hordes. Seth allies with Vanessa and the satyrs and enlists wraiths from the dungeon to protect the house at Fablehaven from the rebelling centaurs, then visits and bargains with the Singing Sisters in order to locate a powerful weapon, the sword Vasilis from the age of wonders. This information takes him to the Totem Wall, where he slays one of Zzyzx's founders to claim the sword.

As Seth prepares for Zzyzx to open, Bracken, Warren, Kendra and Raxtus race to beat the Society to the final locks that hold Zzyzx shut, the last Eternals, an immortal humans who must be killed before the demon prison can be opened. They fail, but Bracken retrieves his second horn, and they kill Mirav and Torina in the process.

Everyone meets up with Seth at the place where the ghost ship, the Lady Luck, will pick them up to take them to the location of Zzyzx, Shoreless Isle. After Seth uses his powers to procure passage they sail to the island. There, they find the Fairy Queen's shrine near the dome holding Zzyzx. Kendra and Bracken speak once more to the Fairy Queen, who tells them that she has destroyed all of her other shrines, and that they have one final secret plan. The astrids are restored as the guardians of the fairy world and are equipped for battle. For the plan to work they need the five artifacts, so Seth, some astrids, and a repentant Sphinx teleport into Zzyzx and reclaim the artifacts. Seth uses Vasilis to slay Nagi Luna and Graulus, while Kendra uses Vasilis to kill the Demon King. After evacuating her world, the Fairy Queen allows the remaining demons to rush into her newly cut off world, trapping them there. With the artifacts in hand, Agad the wizard locks the demons in and the Fairy Queen makes Zzyzx her new home.

Kendra, Seth, their parents and their grandparents move to the re-established Fablehaven. Raxtus visits and reveals that the Fairy Shrine at Fablehaven has been restored. He takes Kendra there, where she meets Bracken. The book closes as Kendra and Bracken contemplate their future together.

Recurring characters

Agad is a wizard who was once a dragon, but permanently transformed into his human avatar forever to gain more magical power. He is the caretaker of one of the three dragon sanctuaries/preserves, Wyrmroost, which are closed to human interference. After the fight on Shoreless Isle, the dragons at Wyrmroost are governed by the king of dragons, Celebrant, because Agad is named the caretaker of Living Mirage after the Sphinx has asked to become an Eternal.