This is volume 10 of the Avatar Last Airbender series.
The Fire Nation is threatened by a prophecy told by the Kemurikage, mysterious figures thought only to exist in legend: remove Zuko from the throne, or the country will perish! Avatar Aang and his friends escort Zuko and his family back to the capital, completely unaware of the looming threat growing in the city. Unrest is brewing as the New Ozai Society prepares to make its move against the crown, and children begin to go missing from their homes under mysterious circumstances.
80 page softcover DARK HORSE COMICS
(W) Gene Luen Yang & Various (A/CA) Gurihiru
80 page digest sized softcover