You might be looking for Everblaze: the Unstoppable Flame.
“She tried not to let herself think about it, because the guild might shatter her sanity. But she could still feel the stinging heat of the flames—still hear the crunches and crackles and screams as the jeweled tower melted around them. And she'd never forget Fintan's taunt as he'd ignited the Everblaze to prevent her from retrieving his memories.”
—Narration, in Flashback
Keeper of the Lost Cities: Everblaze is the third book in the Keeper series written by Shannon Messenger and was released on Nov. 14, 2014. The cover art shows Fitz and Sophie Foster falling from Oblivymere which is burning due to Fintan unleashing Everblaze. In the book, Councillor Oralie is with Fitz and Sophie as they fall from the building, but she is not on the cover.
Sophie uncovers shocking secrets—and faces treacherous new enemies—in this electrifying third book in the Keeper of the Lost Cities series.
Sophie Foster is ready to fight back.
Her talents are getting stronger, and with the elusive Black Swan group ignoring her calls for help, she's determined to find her kidnappers—before they come after her again.
But a daring mistake leaves her world teetering on the edge of war and causes many to fear that she has finally gone too far. And the deeper Sophie searches, the farther the conspiracy stretches, proving that her most dangerous enemy might be closer than she realizes.
In this nail-biting third book in the Keeper of the Lost Cities series, Sophie must fight the flames of rebellion, before they destroy everyone and everything she loves.
In Everglen, they see Alden talking to Councillor Kenric. Since Sophie is slightly uncomfortable revealing this news in front of a Councillor, Kenric leaves. Sophie tells Alden and goes to talk to Biana and ask her what her "surprise" is. When she walks into the room, she sees Fitz seemingly talking by himself. But then, Biana appears and tells Sophie she had manifested as a Vanisher.
On the first day of school, Sophie gets her schedule while Biana and Dex are in for a surprise. There is an announcement saying that Biana has manifested as a Vanisher, but also one saying that Dex has manifested as a Technopath. Angry that someone has revealed his secret, Dex is in a bad mood for the rest of the day. Sophie sees that she is still taking Telepathy sessions with Fitz and is delighted.
The day goes by and Sophie discovers that there are plans for her to heal Fintan. She is shocked, but she can do little against it. Tiergan tells her that he, Alden, Quinlin, and Fitz are available to aid her during the healing. After some contemplation, she chooses Fitz. They tell each other three secrets, at Tiergan's recommendation, and Fitz is able to read Sophie's mind. Shocked and scared, she blocks him. They try to recreate it with five secrets, but it goes poorly. Meanwhile, Stina is shooting harsh remarks at Sophie and Fitz for the healing, as usual. Marella soon joins in, potentially jealous of Biana manifesting. Dex, also potentially jealous about Fitz and Sophie's cooperation, attempts to create an ability-enhancing device, although it does not go well.
After a terrible session with Lady Cadence, Aromark is found to be on Silveny's tracker. Everyone that handled the tracker is purged, but Keefe has to be purged twice because (unbeknownst to him) there is Aromark on his family pin. When Sophie goes home, she finds Biana and Edaline there, and Biana is trying on Jolie's things. Afterward, Biana manages to convince Sophie to let her help with "whatever she's working on."
Before the healing, Grady tells Sophie that Fintan may know who set the fire that killed Jolie and is the missing Pyrokinetic. When the time for the healing comes, it goes poorly. Fintan gains consciousness and sets the Everblaze on everyone present. This includes Sophie, Fitz, Alden, Bronte, Oralie, and Kenric. Sophie, Fitz, and Oralie along with Alden and Bronte make it out in time, but Kenric and Fintan are killed in the fire. Still, Sophie almost sees who the missing Pyrokinetic is. She and Fitz go and collect Quintessence to help make Frissyn that stops the Everblaze.
At Kenric's planting, the king of the Ogres, King Dimitar, arrives. Sophie attempts to go into his mind to find out who put the tracker on Silveny. After she makes it deep inside, he detects her. It is a violation of the Ogre-Elf treaty and Sophie has to be punished. She goes home and continues working to find out who the missing Pyrokinetic is.
They decide her punishment along with who the new Councillor is. The new Councillor is Dame Alina and Sophie's punishment is an ability-restricting device. Dex created it by fixing his ability enhancing device, so Sophie is incredibly angry at him. He offers to take it off, even if it means him being exiled, but Sophie refuses. When she gets home, she is a wreck. She willingly takes sedatives and refuses to leave her room. Keefe, Biana, and Fitz coax her out. Sophie continues searching for the Pyrokinetic when she finally finds him. It is Brant.
Sophie tells Grady and he gets extremely angry. He goes to visit Brant, but Sophie grabs onto him and follows. There, Brant and Grady fight. When all is about to be lost, Dex appears and punches Brant, but he escapes. Dex takes the ability restrictor off Sophie's head and throws it into the Everblaze. Sophie teleports to Mount Everest where her friends are currently defending the Black Swan from the rebels, called the Neverseen.
She reaches Mr. Forkle, who saves her before she dies of cold and lack of oxygen. Then, he shows Fitz how to get past Sophie's blocking. Fitz, Keefe, Biana, and Sophie fight the Neverseen. Keefe finds out that it is not his dad, but rather his mom pretending to be his dad, in the Neverseen. The fight continues and eventually, they make it out alive. Sandor is badly injured but is healed later on. Sandor has to go to the healing center.
All five of them meet in Everglen at night. The parents agree that it is in their best interest to join the Black Swan now. Fitz relays that he found out their next location is in Florence, Italy. The story ends with Sophie saying, "Let's go join the Black Swan!"