|“||When the Flyers try to kill him because he’s no longer useful, Viggo forces Hiccup to help him get revenge by stealing their Dragon Eye and lenses.||”|
The episode starts with Viggo, Krogan, and Johann searching on a new island for the final lens to unlock the King of Dragons. Viggo and some men enter a cave, but when they find it to be only a series of dead ends, Johann and Krogan decide to seal the entrance to the cave and leave Viggo for dead.
Meanwhile, Hiccup and Astrid are trying to take a nice picnic alone with no distractions or interruptions. But all that is in vain as Barf and Belch crash into the beach, as Ruff and Tuff are trying to make a record for the Hideous Zippleback, namely the longest/widest skid mark. Seeing they failed to succeed in that record, they attempt to set the record of most consecutive barrel rolls in one flight, in which they also fail. This interruption is proceeded by another interruption: Fishlegs and Meatlug have a Terror Mail for Hiccup. Deciding that their picnic would have to wait, Hiccup and Astrid go to see this Terror Mail, that is apparently from Stoick claiming he had found a Dragon Eye lens and requested that Hiccup come alone to investigate.
So, despite Astrid's suspicion of something being off, Hiccup goes alone to the island. Upon arrival, Toothless spots a Maces and Talons piece, before Viggo reveals himself. Toothless prepares to shoot, but Viggo sets off a mechanism that he had created, which shoots a bola around Toothless' mouth, rendering him unable to fire. Hiccup unsheaths Inferno, but Viggo requests that he stand down because he doesn't want to fight and revealed that he was the one who sent the false Terror Mail, however, Hiccup states that he had already figured that out. Viggo then goes on to explain what Krogan and Johann had done to him, but Hiccup is disbelieving and strikes. Viggo defends himself with a flaming sword of his own, much to Hiccup's surprise. The fight continues until Viggo uses a Zippleback gas dispenser and sends Hiccup flying backwards to a tree. Viggo unties Toothless' mouth and then pleads with Hiccup to listen to him. He says he needs Hiccup's help, that he won't wait around to get killed by Krogan and Johann and wants to make the first move. Hiccup reacts sarcastically until Viggo fools him into thinking he poisoned Toothless with Red Oleander. He demands that Hiccup helps him, and then they will be able to retrieve the antidote from Johann.
Hiccup reluctantly agrees to help and they fly to a mountaintop, where Viggo lures in and befriends a Skrill using a metal dagger, promising not to torture the dragon. They then attack Johann's base, using the Skrill as a diversion so that Toothless, Hiccup and Viggo can go into the cave. Johann manages to shoot the Skrill down and meet them in the tunnel, where Viggo pretends to betray Hiccup and hand him over, along with Toothless. Viggo returns to Krogan and Johann, where they discuss their plans and what to do with Hiccup, but Johann suspects Viggo's betrayal and threatens him with a knife to the throat, to which Viggo uses his flaming sword and Zippleback gas dispenser to escape and send a signal to Hiccup, who has the key to his manacles and cage in his trouser leg and they escape as well. Viggo frees the Skrill, but gets shot in the back with four arrows.
Meanwhile Hiccup and Toothless find a chest they think contains the Dragon Eye lenses, but it turns out to be empty. At this point, Viggo meets Hiccup and reveals that the poisoning was a bluff and that he's learnt to respect dragons thanks to a Monstrous Nightmare that saved him from the cave-in at the start of the episode. Viggo knows that he will die and convinces Hiccup to go, telling him that he knows he will defeat Krogan and Johann. So Hiccup and Toothless escape the cave, while Viggo and the Skrill hold the soldiers off, but they are then captured by Johann. Hiccup lets out a "frustrated" cry and Toothless fires, which Johann finds humurous, until it turns out to be a signal to Ruff and Tuff (who had been following them the whole time, hoping for a witness of their new record) who then rescue them while setting the record of biggest explosion.
Back at Dragon's Edge, Hiccup feels strange that Viggo is gone and puts the piece of Maces and Talons which Viggo had gave him on the board and covers it with a piece of wood, accepting Viggo's death.
- The booby trap of flying darts that is triggered by pressure plates greatly resembles the one in the Temple of the Chachapoyan Warriors in Raiders of the Lost Ark.
- Coincidentally, the film also features Alfred Molina (Viggo Grimborn’s voice actor) in his first film role.
- Another type of Oleander is mentioned in this episode: Red Oleander.
- The way Hiccup and Viggo infiltrate in the Dragon Hunter base is very similar to the way Thor and Loki went to Svartalfheim in Thor: The Dark World.
- Both Viggo and Loki pretended to betray the hero in front of the villain.
- Both offer them to the villain, saying "I brought you a gift!" and throwing them on the ground, in the front of the villain.
- Both use daggers during the scene.
- Both are former villains in their franchises.
- Both villains had a strong ally with them during the scene.
- The Thorston World Record Book that the Twins talk about is based off the Guinness World Record books.
- Ruffnut claims that Stormfly is the fastest of the Rider's dragons after eating chicken. This contradicts the stats of the Night Fury which show that the Night Fury is the fastest.
- Jay Baruchel as Hiccup Horrendous Haddock III
- America Ferrera as Astrid Hofferson
- Christopher Mintz-Plasse as Fishlegs Ingerman
- T.J. Miller as Tuffnut Thorston
- Andrée Vermeulen as Ruffnut Thorston
- Zack Pearlman as Snotlout Jorgenson
- Alfred Molina as Viggo Grimborn
- Night Fury
- Deadly Nadder
- Monstrous Nightmare
- Hideous Zippleback
- Terrible Terror (mentioned)
- Bewilderbeast (mentioned)