Since his defeat in The Trouble in Skullian Prime, Drago Bludvist has been itching to join the Villain League even with all the restrictions due to being guilty of the murder of a minor High Councilor. However, being told by Mirage that inviting him in their ranks is not going to fulfill them and will have them hunted down by the heroes more often than before. Thus, to prove they have nothing to worry about, Drago decides to find something to give them that is so powerful, they won't have to worry about the heroes' bitching. He still has his Alpha Dragon despite his failure in HTTYD2 and the Skullian Mission, and thus he always has a way to control more dragons. Unfortunately, his target is not Valka's dragon sanctuary, but another Dragon Crew that has been around for a while: The former Monster Hunter Brigade members Burp, Heartless and their friends, who have all been adapting well with the info they got from Hiccup. Discovering they know of Hiccup, Drago sees this as a new means of proving his worth, as well as for revenge. When Burp and his friends are thus endangered, and when the whereabouts of an ancient underground sanctuary of new dragons, including Night Furies and Blackhorrors are found, the Lodgers and the Dragon Crew have to step in, and hopefully have Drago arrested for his crimes against the High Council.