On the secret underground cavern that the Outcasts discovered, Alvin, Salvage and Mildew have learned that there biggest effort of destroying Berk by Whispering Death eggs has failed. Alvin blames Mildew's failed plan and begins to doubt his loyalty to the Outcasts and is about to execute him. But before he can, Mildew comes up with a plan by tunneling their way to the Berk Dragon Training Academy, undetected, thanks to the the made tunnels by the Whispering Deaths, Alvin happily agrees and gives Mildew another chance to live...for now.
Meanwhile, the Riders practice their rescue training. Just as Snotlout and Hookfang seem to have made good progress, they quickly mess up. Astrid does her rescue training greatly by climbing up the cliff by using Stormfly's spines. Fishlegs comes up a new ability in rescuing, called the Stop, Drop and Hover. Hiccup is satisfied with this new move but Snotlout states that it's only falling, Fishlegs shows him what's falling by allowing Meatlug to fall on Snotlout, and Hookfang ditches him. The twins rescue move, quite odd, it actually only involves Ruffnut and Tuffnut not falling off so that no actual rescue is necessary. Ironicly, Ruffnut moves and hits Tuffnut falling him off the sea stack. Hiccup and Toothless' rescue skill is a new move called the Barrel Roll with Toothless firing multiple blasts at enemies. The Riders are impressed except for Snotlout, but Fishlegs justifies Hiccup and Toothless' move. But when Fishlegs states Snotlout dead last at the competition, the Riders are somehow convinced that it is a competition, but Hiccup states that it's not and its only teamwork. But his testimony falls on deaf ears and laughs at it too. Fishlegs suggests that they create a competition to see who's the best and who's the worst. Snotlout is confident that he's the best.
Fishlegs's level playing field involves giving each one a Terrible Terror and is given 24 hours to train it with tricks as quickly as possible. While Hiccup keeps telling them that its not a competition but again fails to re-convince them. Meanwhile Alvin, Salvage, and Mildew have found several yak farms and finally found the location of the Academy.
At Fishlegs' house he tries to decide and give a name for his Terrible Terror, while Meatlug wants Fishlegs to join her play toss the sheep. Fishlegs denies her pleas as he is wrapped up of beating Snotlout and even ignores Hiccup's statements that its not a competition. Hiccup and Toothless see Meatlug (who is neglected by Fishlegs) upset but Fishlegs thinks that she's fine. The next day, Meatlug is still neglected by Fishlegs again and feels once again upset. The competition begins, and Fishlegs and Snotlout are bragging at each other, and the riders are surprised at Fishlegs' new behavior. Hiccup goes first and doesn't even care if he loses or wins, he shows off his trained Terror, Sharpshot, along with Toothless's help. Sharpshot shoots 3 tossed carved ducks in a straight row. Astrid's terror does some sneaky stealth skills by being unnoticed by the Riders. The Twins' trained their terrors by flying straight at each other and banging their heads. Fishlegs's trained his Terror, Iggy, to identify and bring the assigned objects showed to him, which he perfectly does it well and humiliating Snotlout by dropping the object he assigned for him. Snotlout's Terror only involves him tightly and brutally biting his leg, which Gobber barely got it off yesterday. Fishlegs finds Snotlout's training skill for his Terror ridiculous and requests Hiccup to tell him that he won. The riders then argue at their Terror's trained abilities deserve to be the winner of the competition and simultaneously tells justifications at each other of how they deserve to win.
Meanwhile, Meatlug catches up a scent and blows Alvin, Salvage and Mildew's cover (literally). They fall back, but Alvin fights back and takes Meatlug as captive. Fishlegs is too late to save his dragon after being wrapped up about the competition. The twins' reveal to them that they have been spending time inside the tunnels, to entertain themselves, and also inform that the tunnels also link up to the shoreline on the beach. The Riders know where to look, and sets off to find Alvin. The riders tell Fishlegs that its not his fault, but the Twins mock him that it is his fault. Fishlegs admits his foolishness of being caught up to the competition. They find the Outcasts' ship and the two sides engage at each other. As Toothless about to fire, Alvin threatens to kill Meatlug if they make one move. They seem to fall back and leave Meatlug, but Hiccup has a plan by using their Terror's abilities against them. The Outcasts wonders if they'll come back, unbeknownst to them the plan is already in progress. As Astrid's stealthy terror is on top of Alvin and Salvage misses to hit it and accidentally hits Alvin instead. Iggy grabs Alvin's sword, and Sharpshot fires the ropes of Meatlug and allowing her to escape but one still manage to hold her. As Mildew is about to stop her, he gets brutally headbutted by the Twins' Terrors. Meatlug escapes, but she gets caught by Alvin. Snotlout strongly but painfully takes the biting Terror of his neck and throws it at the rope holding her and breaks it. Meatlug is finally free, and the thrown Terror returns to Snotlout and painfully bites him again. Hiccup uses Toothless' new ability against the Outcast ship destroying and sinking it, the Outcasts abandon their ship. The Riders head home and Fishlegs happily reunites with Meatlug, Tuffnut still states that the competition was worth something after all, Hiccup again tells them that it's not a competition.
Meanwhile, Alvin, Salvage and Mildew float to their island and Alvin angrily punches Mildew, knocking him unconscious, a shark is seen following them. Back on Berk, Fishlegs and Meatlug happily play toss the sheep, Hiccup asks Fishlegs if he likes to join them training their Terrible Terrors, but Fishlegs thankfully denies Hiccup's request as the two have a lot of catching up to do. Hiccup is happy to see Fishlegs back to his normal behavior again and flies back to the Riders ending the episode.
- Jay Baruchel as Hiccup
- America Ferrera as Astrid Hofferson
- Christopher Mintz-Plasse as Fishlegs Ingerman
- T.J. Miller as Tuffnut
- Mark Hamill as Alvin the Treacherous
- Zack Pearlman as Snotlout Jorgenson
- Stephen Root as Mildew
- Paul Rugg as Savage
- Andree Vermeulen as Ruffnut
- This is the first time yellow Terrible Terrors are seen. This is also the first time Terrors were trained.
- The riders appear to know that Mildew has betrayed Berk, again.
- It was Mildew's plan to plant the Whispering Death eggs under Berk. However, in The Iron Gronckle, Savage says it was Alvin's plan.
- During one scene, Hiccup's tunic ends at his belt, but seconds later, it returns to its normal length.
- During one scene, Hookfang's horns were askew.
- A running gag in the episode is that Hiccup keeps saying the training was not a competition.
- The twins are revealed to spend a lot of time in the tunnels of Berk, and know where each one goes.
- This is the first time a dragon other than Toothless is put in the restraints from the film. They were, however, slightly different.
- The wooden ducks that Sharpshot blew up were the same as the ones that Gobber and Stoick carved in How to Start a Dragon Academy and We Are Family Part I.
- None of the other teens want to admit that Hiccup is the best dragon trainer on Berk.
- Even though that Hiccup always said that "It is not a competition" everybody neglects it. The same thing happened again in Dawn of the Dragon Racers.
- The Six Terrible Terror's trained by the teens names are Butt, Head, Sharpshot, Iggy Sneaky and Pain.