- "They say two heads are better than one, which is often true, but four heads? Eh, that's a few heads too many."
Berk is getting its yearly visit from the Berserker Tribe, and Stoick wants to make sure all the dragons are hidden, just in case it starts another war. But then, Dagur the Deranged turns out to be the new chief of the Berserkers, after overthrowing his father: Oswald the Agreeable. In the middle of that, Ruffnut and Tuffnut have had a falling out, leaving Barf and Belch running around wildly in the village, which makes things worse. Hiccup and the gang try to bring Ruffnut and Tuffnut together to control Barf and Belch, before Dagur finds them.
The Riders are performing a training excercise of trusting their dragons' vision, the Twins are having a hard time to see anything through the clouds, Hiccup informs them they must trust their dragon to see for them. The Twins did not pay attention and instead trust themselves to navigate, Tuffnut and Ruffnut both gave separate commands to Barf and Belch resulting them to fly violently as one head does a command besides the other. The Twins and Barf and Belch collide with Fishlegs and Meatlug, and the Twins and Fishlegs fall and land on a tree. The Twins' branch is about to snap, and the two order their dragon separate commands again, causing Barf and Belch to go astray, unable to help them.
Fishlegs lend them a hand with Meatlug by signalling her with his hands and successfully rescues the Twins. Fishlegs overexcitement that his hand signal worked, causes his branch to snap but is saved by Hiccup. Hiccup asks what was Fishlegs doing with his hands, he explains that he came up with a new idea of communication by doing hand signals just in case the two are separated. Hiccup sees it as revolutionary and heads back to the Academy to work on it right away.
At the Academy, Hiccup and Astrid are doing well of teaching their hand signals, though Snotlout does his hand signal of the command to Hookfang to annihilate the given target, Hookfang annihilate Snotlout instead. The Twins try their's but ends up doing separate hand signals to Barf and Belch causing their dragon unable to perform their orders properly. Hiccup tells them to do only one hand signal at a time, but the Twins didn't take it seriously, and they ordered their dragon to attack their Riders. Tensions rise from the Twins as they start to feel that they do not want to work with each other with their dragon, who they both blindly still sees that Barf and Belch are two dragons. And then they reach a boiling point, that they decide to leave dragon training and leaves their dragon alone. Hiccup, though, is confident that they'll hopefully work things out eventually.
Later, Hiccup notices that Stoick is wearing his very tight ceremonial belt. Stoick informs Hiccup that tomorrow is the annual signing of the Treaty from the Beserker Tribe, where their Chieftain, Oswald the Agreeable will be usually arriving at Berk to sign the Treaty that kept a non-aggression pact with the tribes of Berk and the Beserkers for the past 50 years. And he'll also be bringing his son, Dagur, who Hiccup sees as a lunatic, that he once used Hiccup as a knife-throwing target, and expects that he'll be keeping an eye on Dagur from breaking things again this year. However, Stoick assigns him to do an important job, he orders Hiccup to hide every dragon from Berk away from Oswald and the rest of the Beserkers, as despite they haven't waged war for 50 years, they haven't heard that Berk has made peace with the dragons and Stoick thinks that it's safe to hide the dragons as the Beserkers may see it as a threat or aggression.
When the Riders are rounding up the dragons, they notice Barf and Belch, without the Twins, flying off out of control and flies straight pass them. Snotlout volunteers to control the dragon, but he needs another Rider, Fishlegs reluctantly volunteers and he lands on Barch. However, Fishlegs causes Barf to burst gas out of him and Fishlegs begins to feel sick, Snotlout, on the other hand, however, doesn't know how to maneuver Belch and he accidentally causes Belch to ignite the gas and explode. Both Snotlout and Fishlegs are thrown back to Hookfang. Without the Twins, Barf and Belch fly freely and Hiccup must manage to control them, however, the Beserkers have arrived and heads back to Stoick to inform the situation.
At the Docks, Stoick and Gobber awaits Oswald to step foot on the harbor, Hiccup tries to inform his dad their problem but Stoick tells him to tell it later. When a Beserker official anounces and presents their Chieftain's arrival, Stoick and Gobber shockingly learns that Oswald's son, Dagur the Derranged is now the new Chieftain of the Beserker Tribe.
Stoick asks Dagur his father's whereabouts, but Dagur claims that his father 'retired' and he is fiercely dedicated to the Beserkers' former glory of being a dominant force when it comes to wars. Dagur then asks Stoick where is he hiding their dragons, as he've heard rumors that Berk was amassing an army of trained dragons. Though he has no authority to inspect and investigate whatsoever, he gives Stoick a warning that if he discovers that it was true, the Beserker Amarda, 50,000 strong, will engage on Berk on Dagur's word. Stoick just tells him to stand down and they go back to the Treaty, Dagur recaps the routines of signing the Treaty as he first has to go to a tour on Berk such as the Armory, have a feast on the Great Hall, and especially witness the Killing Arena, where he asks Stoick that do they still kill dragons. Though Stoick tells him that his father never took the tour necessary, but Dagur tells him precisely that he is not his father. Stoick's temper begins to rise, but Gobber tells him to br rest assured and go on with the Treaty.
Meanwhile, Hiccup grows worried of the critical situation, it gets worse, when Astrid tells him that Barf and Belch are actually now wandering in the village. When they see Stoick and Gobber showing Dagur their food storage, they try their best to keep Barf and Belch away from their field of vision. Dagur isn't going well with the Tour and immediately request that they escort him to their Armory.
From there, Dagur acts obnoxious when he uses the weapons by acting as he is killing and slaugtering dragons without mercy. Stoick's temper grows but Gobber tells Dagur why not to proceed with the Treaty. Dagur thinks it's just like his father's 'cowering' behaviour, where he recalls his father back at home to not let Dagur do anything violent. Stoick tells him that his father was a great man and does not want to hear Dagur disrespecting him, but Dagur sees his father as a coward, incapable of leading the Beserkers. Suddenly, Stoick notices Hiccup chasing a wild Zippleback just outside, Gobber manages to close the doors before Dagur sees it as well.
Just outside, Hiccup sees that Barf and Belch are just on top of the Armory, and Hiccup tries to tell them to go away. However, Dagur is about to go outside and Hiccup closes his eyes, thinking that Dagur might see the dragon. However, Dagur didn't actually notice the Zippleback as he finally finds Hiccup. The two recall their memories from Dagur's past visits but he goes bored and begins to leave, but he feels that something is not right behind him. Hiccup thinks that Dagur noticed Barf and Belch, but he actually instead noticed Hiccup having his prosthetic leg and asks what happened, but calls it off when Dagur already heard what happened.
Hiccup asks what he has heard, Dagur informs him that he has heard rumors that Hiccup himself, has defeated the mighty Red Death, but Hiccup claims it as a fraud that how can he defeat such a beast, then Dagur tells him about the rumors of 'trained dragons', Hiccup assures Dagur that he doesn't know how to train a dragon, but Dagur is still suspicious. Hiccup changes the topic by telling him to proceed with the Feast at the Great Hall, when they leave, they hear a grumbling sound, which is Toothless struggling to take Barf and Belch off the Armory, but Hiccup tells him he is just starving. After a close call, Hiccup then runs behind the Armory to inspect Barf and Belch, and recommends that they need the Twins.
At the Twins' homestead, they find Tuffnut, and Hiccup requests him and Ruffnut to go out and get their dragon under control. But Tuffnut refuses as he already decided that he is over with dragon business and also his relation with his sister, Astrid asks what's their problem, Tuffnut explains that his whole life, he never had an object to not share with his sister and his only wish is to have something all for himself. Tuffnut then decides to pack his stuff up as he begins to leave his home, he doesn't tell Hiccup and Astrid where is he exactly going, he only says that it's his 'dark, soggy, and alone place' and is well on his way.
At the Feast at the Great Hall, Hiccup informs his father the current progress, and Dagur prepares a toast, though intended for the death in battle, they instead toast for his father, which he angrily accepts. Gobber asks Dagur if he can now sign the Treaty, Dagur accepts but only to bring the Dragon's blood for ink to finally sign the Treaty.
Stoick informs him that he and his father have not used Dragon's blood for ink for years now, but Dagur sees it not as a problem unless Stoick have stopped killing dragons. Stoick confidently tells Dagur that they do still kill dragons, and Gobber explains that due to they have killed so many, there has not been a single dragon appearing for at least 200 miles, except when Barf and Belch crashes inside the Great Hall, exposing themmselves to Dagur. Dagur sees it as a sign as 'a head for each chief' and commences a dragon hunt for the Zippleback. Now, Hiccup must find Barf and Belch before the Beserkers do it before him.
When searching for Tuffnut for hours, Astrid doubts that they'll be able to find them on time as they have no clue where is Tuffnut's 'Dark, Soggy, and Alone place' is, but Snotlout tells them it's not that far as he actually knows where it is. Hiccup asks Snotlout why hasn't said anything after flying for hours searching for him and Astrid rages anger if Snotlout doesn't tell them, Snotlout points them that Tuffnut might be at the Lost Cavern where they used to play when they were just kids. Hiccup and Fishlegs takes the North entrance of the Cavern while Astrid and Snotlout takes the South.
Hiccup and Fishlegs finds Tuffnut, who tells them to quit following him, they then heard Ruffnut's voice on the other end where she tells Astrid and Snotlout to quit following her also. They then realize Tuffnut and Ruffnut both have the same place to endure their pain and sorrow. Hiccup tries to talk some sense into them as their dragon is in trouble and needs them. They'll both go, as long as one of them do not go also, Hiccup gives them advise saying, that they have to work together, they'll give them the things they want for their own, but what they can't give to them is another Barf and Belch, and they must realize there's only one dragon for them. In the end, Ruffnut and Tuffnut finally reconcile and make up with one another with a spit-shake and friendly headbutt. Wasting no time, they hurry to find Barf and Belch.
At the Forest, the Riders spot Barf and Belch but are little late, as the Beserkers have also tracked down Barf and Belch, and they have them pinned down. The Riders halt their ground and can only watch as they cannot afford to expose themselves to the Beserkers. When Dagur attempts to behead them, Stoick intervenes and tells him that they are suppose to behead the dragon together in the Arena, to do the killing properly. Dagur accepts and lets the Beserkers deliver the dragon to the Arena, Stoick did his best to stall Dagur but it's now up to Hiccup come up of a plan to prevent Barf and Belch from being killed while also not risking them of being exposed as the Beserker Armada would wage war against Berk. Snotlout suggest a head-on attack, though insane as it sounds, Hiccup thinks Snotlout may be on to something.
At the Arena, Dagur continues to behead the dragon taking one head while he lets Stoick take the other. Stoick cannot bare to witness this from happening, and he takes his sword and plans to sneak up on Dagur and incapacitate him before Dagur kills the dragon, risking a war with Berk and the Beserkers. However, Hiccup and the Riders arrives and shouts that a pretend 'dragon attack' is occuring, Stoick and Gobber quickly play along. The Riders quietly order their dragons to attack the Beserkers using hand signals to avoid suspicion.
Gobber orders everyone to be evacuated, but Dagur initially resists and refuses to retreat and attempts to finish what he started. The Twins arrive at the scene and gives out their hand signal to their dragon one at a time, and they successfully manage to fend off Dagur. The Twins are now working out their hand signals together, and orders their dragon to come to them. Dagur regains his strength and throws a spear at Barf and Belch, but Toothless manages to block it off. Dagur expresses his surprise to finally see the legendary Night Fury that he now believes they exist.
Hiccup pretendly defends Dagur's back against the Night Fury, Hiccup gives Toothless the order to shoot a plasma blast and Hiccup gets him out of the way. Overwhelmed, the Beserkers retreat and Hiccup pleads that Dagur run to safety, as he volunteers to fend off the Night Fury. Dagur is finally convinced and orders a full retreat back home, but Gobber asks him about the Treaty lacking his signature. Unable to do it formally due to the dragon skirmish, Dagur just considers it to be signed by him and they flee. Finally, the Beserkers are gone, the twins celebrate with another spit-shake, Stoick is impressed and gives Hiccup another job well done and claims that they won't be seeing Dagur anytime soon.
Hours later, while cleaning up the Academy, the Twins finally mend their relationship and discard their old hatred with each other, they now work together with Barf and Belch as a team. Snotlout tells the twins he still thinks Dagur is cool, and they respond by getting Barf and Belch to blast him away. The twins exchange headbutts and Barf and Belch imitates them in the action of affection. Hiccup gives off the closing narration and the episode ends.
- "I used to think four heads was a little crazy, and I wasn't wrong. But I'll take crazy over Berserk any day of the week!"
- Ruffnut and Tuffnut's special alone place is found in this episode.
- As Hiccup was the first person to ever see a Night Fury in the film, the other tribes had never seen one in person. This is why Dagur comments, "They do exist!"
- This is the first time the Red Death was mentioned in the series.
- The text of the treaty is a runic substitution cipher of the Gettysburg Address. The final lines under the signature blank are "David Lee", the prop designer, and what appears to be "MONTLNHN" or similar gibberish.
- Dagur the Deranged is introduced, along the Berserker Tribe.
The full transcript can be found here