This volume mostly takes place in and around the bubble/pocket world of Ghostwater, created by Northstrider, whom everyone, but Lindon, believes is dead/gone.
Lindon and Yerrin continue to advance along their chosen paths and make new friends and enemies.
SPOILERS BELOW
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Lindon finds a series of wells and circumstances that allow him to rank up to TrueGold prior to leaving the pocket world. Orthos also gets a serious healing and at one of the wells turns back the ravages of years. Lindon learns that eating sacred beasts can seriously help your body.
Lindon makes a new construct friend, and then installs him into his body, giving him access to something that is suspiciously similar to the Way reports we get throughout the last few books.
Northstrider would likely be very interested in this.
The climactic battle for Lindon is with Akura Harmony (Mercy’s ex-fiance). Lindon spares him and offers him a way out, but Harmony swears vengeance so Lindon destroys his way out and leaves him there in the crumbling world. When Northstrider appears to check on the world before it fades, he decides to leave the begging Harmony to his fate.
Lindon escapes and reunites with Yerrin and Mercy.
Meanwhile, Yerrin and Mercy have their own adventures. Yerrin advances to TrueGold as well and comes to a better understanding of her path.
Mercy and Yerrin bond a bit, with Mercy sharing more about her own path (Book of the seven pages). Mercy also shows off some of her techniques from the book, which allow her to temporarily rank up.
At the end of the book they are theoretically going to go back to the Sky Sworn and report on their wacky adventures.
They appear to have made a new enemy in the Dragons, but that will presumably be on hold until The Tournament.