Dragon's Edge has been beset by small eruptions in the month following the Riders' victory over the Hunters, and with nothing left for them in the outlying islands, the Riders are forced to make the heavy decision to return to Berk. Hiccup and Fishlegs develop a mixture of Deathsong amber and Gronkle Iron to stop the lava bursts, but while gathering materials, Hiccup and Astrid discover an older Garffljorg mortally wounded, hinting that the Hunters, who are now led by the masked man who tried to abduct Hiccup and has the ability to control dragons, are continuing activity. Working together with the Gronkles and Quakens of Dark Deep, the Riders manage to stabilize the volcano, and decide to hold off on returning home to stop the Hunters once and for all.