Book 4: Neverseen

You might also be looking for Neverseen: the group.

Keeper of the Lost Cities: Neverseen is the 4th book in the Keeper series the release date was Nov 3rd, 2015. The cover art shows Sophie, Keefe, and Biana under large waves.

Synopsis
Sophie Foster is on the run-but at least she's not alone. Her closest friends from the Lost Cities have gone with her to join the Black Swan. They still have doubts about the shadowy organization, but the only way to find answers is to start working with them. And as they settle into their new lives with the Black Swan, they uncover secrets far bigger than themselves, proving that the rebels are far from done, and might unleash a terrifying plague that threatens the safety of an entire species. Sophie and her friends fight with everything they have—with new allies joining them—but every choice has consequences. And trusting the wrong person could prove deadly.

In this game-changing fourth book in the Keeper of the Lost Cities series, Sophie must question everything.

Plot Summary
The story starts off with Sophie, Keefe, Fitz, Dex, and Biana getting ready to run away and join the Black Swan. As Alden helps them remove all their accessories they can be identified by ( registry pendants, nexuses, etc. ) and they get ready to leave, they are greeted by Councillor Oralie who gives Sophie a cache from Kenric - something that holds the darkest secrets of the Council that they want to forget. Once they teleport to Florence and eat some gelato, they make it to the Black Swan with Mr. Forkle's help. On the way, they discover Della has been with them all along.

They are introduced to where they will be living during their stay and are taken to the Black Swan's Collective where Sophie receives her memory of the Boy Who Disappeared, with the help of Fitz because they are revealed to be Cognates - Telepaths with a special connection. After the memory is discovered to be a dud, Sophie returns to her treehouse and meets Calla, a gnome who helped with Project Moonlark.

The next day, Sophie and Fitz train as Cognates ( with Granite ) and Sophie tried to teach Fitz how to communicate with Silveny, which turned out to be a success. The next morning, she is woken up by Dex who reveals that he found a way to hack into the Council's archives to find out who the Boy Who Disappeared is. Mr. Forkle finds them, accompanied by the rest of the Collective. He makes them promise not to pursue the hacking, giving Dex a way to help them and improve his Technopathy skills.

The following day, the five are training when Sophie almost reveals to Fitz that she likes him. She is interrupted by Keefe and does not tell Fitz. After this, Calla runs in and explains a situation about two gnomes watching over the Neutral Territories who have spotted members of the Neverseen. The gnomes explain that they saw Lady Gisela injured and Sophie and Fitz look into their memories to confirm it. Keefe is devastated when told they can't go after his mother.

For the next day or two, Keefe is furious and sad, not making an appearance for any of their meals. Sophie cheers him up one night later by having a "window sleepover" with him. The next morning, Calla wakes her up and takes her and Biana to the Neutral Territories to investigate the plague. They are attacked by a Psionipath member of the Neverseen and Biana saves them. A few days later, Calla says that the only way to cure the plague is with Panakes blossoms.

Mr. Forkle takes Sophie and Keefe to visit Gethen, a member of the Neverseen who they have captive. Mr. Forkle extracts some information from him while Gethen taunts Keefe and the three return. Keefe, now extremely frustrated, begs for fathomlethes, pearls which will help him access childhood memories with him mother for clues. His wish is granted and he leaves to the treehouse to search for answers.

Meanwhile, Dex makes a device and finds a scroll and discovers a secret about drakostomes that may imply the Council knew about the plague.

Eventually, the five go to get back Prentice in Exile, during which they are found by the Council. Fitz is attacked by an arthropleura and gets extremely hurt. The Black Swan and Council negotiate, finally agreeing that the Council will let the Black Swan go if the five are banished and go to Exillium.

While Fitz heals ( and everyone, including Keefe, finds out about Mr. Snuggles ), Mr. Forkle reveals to Sophie that he was Sir Astin. When they finally get a chance to check on Prentice, his mind is empty and Sophie says, "Prentice is gone."

Edaline comes to visit the Black Swan and drops off Iggy, who Biana offers to take care of. Edaline helps Sophie hide the cache in a void she can only access by saying specific words (221B Baker Street) with her voice.

As Fitz continues to slowly heal, Sophie helps Keefe with the memories, as he has gone a bit crazy. Calla leaves Alluveterre (where they are staying). Sophie walks in on Tiergan, Magnate Leto, and Wylie trying to work with Prentice. Fitz finally heals.

The five get ready to go to Exillium when Sophie figures out she is actually fourteen by Elvin standards. In Exillium, they undergo rigorous training ( Sophie starts a fire during the initiation ) and meet twins their age- Linh and Tam Song. Sophie helps make the cold Exillium much more friendly and also gets a message from Silveny saying she's pregnant.

Mr. Forkle meets with Linh ( a Hydrokinetic ) and Tam ( a Shade ). Keefe and Tam did not get along. Sophie hails Oralie and Terik about what Mr. Forkle discovers with Tam - that the plague feeds off of shadowvapor.

Sophie and Fitz continue to train as Cognates with Mr. Forkle, this time doing emotional exercises with the help of Keefe. They manage to make it past Mr. Forkle's blocking and figure out that Mr. Forkle has been planning to ask Lord Cassius to join the Black Swan, making Keefe incredibly upset. Calla finds out that the Council knew about the plague all along and is devastated.

The five disguise themselves and return to the regular Elvin world, where they find out that Fintan has been alive all along. They work with Alvar to go to Ravagog and find the cure from the plague from King Dimitar, finding out it was a bust all along. With Linh's help, they all escape in one piece. It is revealed that Alvar has been a part of the Neverseen all along.

The five are unbanished and granted a reentrance to their families and Foxfire. As they reunite, and break the news to the Vacker family, Calla reveals the devastating news. To create the Panakes blossom, she will have to turn into the tree herself.

Once Calla transforms, something seems to be off with Keefe. While he and Sophie are talking, she asks where he is going, and he gives a generic answer. But when he pulls out a yellow crystal, Sophie grabs onto him as he leaps, and she is taken to a meeting where it is revealed that Keefe is going to join the Neverseen. Begging for her to listen to her and get out, Keefe mimics Sophie's voice to give up Kenric's cache to the Neverseen in return to let Sophie escape. She returns and tells Mr. Forkle and Granite the news and they reveal themselves to be Magnate Leto and Tiergan respectively. The story ends with Magnate Leto saying, "As of this morning, Prentice is awake."

Cover
The cover shows Sophie, Keefe, and Biana under large arches, in (spoiler!) Ravagog, disguised as Neverseen. They are surrounded by Lihn's water.