At Dragon's Edge, the Riders and the rest of the inhabitants in the island have been relentlessly attacked and chased off by a new dragon called the Rumblehorn. One night, they set up a trap for the dragon and successfully works, when the gang goes to check it out, they find that Gobber was the one who stepped on it. The Riders are disappointed but Tuffnut still suggests that they 'club' him, Hiccup decides just to get back to their base.
When they arrive at the center of their base, they find it ransacked quickly by the Rumblehorn while they were gone. Gobber then explains to Hiccup why he came to the island, he informs Hiccup with disturbing news with his father, Stoick, as he has been recently extremely irritated at the village, driving everyone mad. Hiccup and Toothless decides to check it out, while Gobber plans on to stay to help carry out defenses against the Rumblehorn with his past dragon-killing experience, and basically hiding out from Stoick.
When they arrive at Berk the next day, Hiccup quickly hears Stoick in anger and checks it out. At the Armory, Stoick becomes very agitated at Sven after he failed to arrange the weapons by deadliness causing him to throw some of the weapons out and he leaves in anger. When Sven sees Hiccup he becomes greatly thankful and ask him to do something with his father, Hiccup reasons fairly that Sven did fail what his father asked, Sven justifies it because Stoick keeps ordering him day by day to arrange the weapons, such as by length, pointy-ness and even by name. Hiccup calms Sven down reassuring he'll fix the situation.
At a field, Gothi is ridiculed by Stoick as he says she 'plows like an old woman'. Stoick even demonstrates how to plow in front of Gothi. When Gothi spots Hiccup, she drags him for a talk where she angrily writes and describes Stoick's behavior. Hiccup reassures her that he'll fix it.
At Dragon's Edge, the Riders wander through the ruins, checking if some of their structures still survived. Fishlegs observes the Rumblehorn's footprints concluding its appearance to be hefty and powerful, Snotlout complains why do they need to rebuild the area if the dragon will again sabotage it. Gobber tells them help him build a wall in defense against the Rumblehorn's attacks.
At the Academy, Stoick is angrily doing axe throwing, almost throwing an axe on Hiccup when he suddenly interrupts. Stoick then brutally hugs Hiccup in joy, as he gets to see him again. Hiccup asks his father what brings him here, Stoick answers that he wants some peace and quiet away from all the complaining in the village. Hiccup notices that his father has been cleaning Thornado's saddle, keeping it really shiny, as Stoick wants it to be a piece of memory of his dragon. Stoick then asks what Hiccup brings him here, but suddenly Sven interrupts saying that he got all the weapons arranged by deadliness, but it results angering Stoick making him want to hurdle an axe on Sven, in which he flees in fear. Hiccup invites his father to their island for a few days off from being chief, and also to help Hiccup handle a problem with a dragon. Stoick accepts the offer and joins Hiccup.
Meanwhile, the Riders and Gobber had finished constructing a massive and impressive rock wall, which Gobber names it Gretha after her first love, due to having disturbing similarities with the wall. Suddenly, an attack from the Rumblehorn is heard from the West section and the Riders mount up in defense, Gobber stays put and tries to hold onto wall as it is being battered by the dragon. Though it holds, the wooden watchtowers does not and it collapses on Gobber. When the Riders dig him up, Gobber's behavior mentally changes and is now delusional.
When Hiccup, Stoick and Toothless comes near to the Dragon's Edge, they are met by heavy fire from the Twins' dragon and Hookfang as they've mistaken them to be an enemy. They finally realize and ceasefire, Hiccup and Stoick notices Gobber being delusional, Snotlout explains what happened to him. With the Rumblehorn situation getting worse, Hiccup devises a plan and assigns some of the Riders to split up and track down the dragon while Fishlegs and Snotlout take care of Gobber.
Hiccup, Stoick and Toothless venture out throughout the center of the island, Stoick asks Hiccup when did they first start having trouble with the dragon, Hiccup answers it's been a few weeks since, and they had no clue the dragon was in the island, and now the Rumblehorn wanders out everywhere. Hiccup also adds that he hasn't done any harm to the dragons, but describes the dragon powerful, intelligent and very elusive as they haven't even observe a good appearance of the dragon. Hiccup and Stoick bond with their mission, but suddenly they spot trouble nearby and checks it out.
When they land, they find the Rumblehorn just disappear, every time. Stoick suspects it's still near and follows tracks and clues to find out where it's heading. However, they've been going around in circles as the dragon keeps evading them no matter how close they get to it, Stoick points out that the beast can sense them, resulting it to change direction. Tired, Stoick has an idea how to confront the dragon.
Stoick is alone in an open where he waits for the Rumblehorn to confront him, and eventually it does. The huge and powerful dragon charges head first on Stoick just like he planned. Overhead, Hiccup and Toothless attempts to throw a net on top of the dragon and capture it, however, the dragon suddenly spots them and he evades capture. Hiccup shouts to his father to escape, but Stoick has a backup plan as he ties the dragon's horn with a rope and grabs hold, painfully tackling the Rumblehorn.
In retaliation, the Rumblehorn flies off, dragging Stoick with him. Above the skies, Stoick struggles to hold on and he eventually lets go. Stoick plummets but the Rumblehorn also dives down at him also, with Stoick thinking the dragon wants to continue the brawl. Fortunately, Hiccup and Toothless catches Stoick and retreats, but Stoick shouts saying it's not over yet at the Rumblehorn. The Rumblehorn throws the rope on the ground, and smells it's scent, revealing that it can track down foes with their left out scent.
At night, when Hiccup, Stoick and Toothless land, they inform the Riders what happened, and then plans to resupply to find and capture the Rumblehorn again. However, almost immediately, the Rumblehorn arrives and found them first, tracking them down all the way, surprising Hiccup and the other Riders. The Riders need to draw it's attention away from their base.
Suddenly, all the Night Terrors are fleeing with the Rumblehorn bypassing the Riders. Hiccup realizes the Rumblehorn is going after Gobber, still delusional and alone on the ground. The Riders try numerous attempts of getting it's attention but is relentless at chasing Gobber. Gobber is still oblivious of what's behind him, as the Rumblehorn is getting closer at Gobber. Hiccup and Toothless has no choice but to 'neutralize' the dragon with one shot. Meanwhile, Stoick is puzzled by what the dragon is doing, until he realizes something causing him to prevent Hiccup and Toothless to misfire.
With plasma blast missing the Rumblehorn, the dragon confronts Gobber, but instead of killing him, the dragon loudly roars at him instead, but Gobber sees him as his favorite pet yak Pepe due to still being crazy. Stoick was right about his decision and explains to Hiccup if the Rumblehorn wanted to hurt somebody it should've done it by now, and suggests there's something else instead going on. To figure it out, Stoick decides to confront and talk with the dragon. The Rumblehorn gestures and points something, where Stoick observe it's warning them something. Suddenly, the Rumblehorn orders the dragons to fly, and gets Stoick to ride with him. As they fly out, Hiccup realizes a huge tidal wave is heading straight for Dragon's Edge.
When they head back, Hiccup informs the Riders that the Rumblehorn wasn't trying to harm anyone it was trying to warn and save them of the oncoming tidal wave that the dragon knew all along. Hiccup and the Riders must come up with the idea of blocking the huge tidal wave before it devours their base. Astrid suggests they heavily reinforce Gobber's rock wall. With only minutes away until the wave hits, the Riders worry that the wall isn't high enough to counter such a huge wave, and water even begins to breach through. Stoick orders them to fix the breaches as he and the Rumblehorn fly off with a plan. Stoick and the Rumblehorn attempts to push a giant sea-stack nearby to counter the wave, they successfully manage to do so and the huge tidal wave is no match against it and it finally settles down.
The next day, the island is saved thanks to the Rumblehorn's warnings, Fishlegs and Hiccup watches as Stoick and the Rumblehorn flies magnificently as Stoick has now taken into a liking of riding it. Fishlegs sees the dragon as a new class of dragons. After observing the dragon tracking abilities, Hiccup creates the 'Tracker Class'.
Back on Berk, Gobber is back to normal, where he doesn't recall much about what happened prior. Stoick thank Hiccup for inviting him to their island so that he could have a new dragon, Hiccup informs him that he thought his father was agitated after Hiccup left Berk along time, but turns out Stoick misses his old dragon, Thornado. Stoick does miss Thornado dearly, saying he can never be replaced, but the Rumblehorn is a lot like him, describing they are both leaders and protectors. Gobber then comments they are both 'hard-headed', Stoick prefers to be 'skull-crushing', by this Stoick comes up with a name for his dragon, Skullcrusher.
Before they depart and do their usual tasks, Stoick informs Hiccup that he does actually misses his son, a lot in fact. Hearing this, Hiccup becomes happy and proud for his father.
- The Rumblehorn makes its debut.
- This is mispelled in the TV guide description, replacing the second (lowercased) R with another E:
- "As a Rumblehoen dragon wreaks havoc on Dragon's Edge, Hiccup seeks the help of Stoick, who forms an unexpected bond with the rampaging beast."
- This is mispelled in the TV guide description, replacing the second (lowercased) R with another E:
- The Tracker Class is established.
- Stoick trains the Rumblehorn, naming him Skullcrusher.
- Snotlout's sheep launcher is seen when Stoick is shouting at Sven at the armory.
- Hiccup seems to be able to read Gothi's scribbles.
- This is the first time Hiccup has been called Dragon Master in the series.
- Tuffnut hints that he doesn't know how to swim.
- The episode's title is a reference to country music artist Brad Paisley's song "Crushing It".
- Stoick comes up with a new verse to the "I'm a Viking" song-
- Oh I've got my club
- And I've got my rope
- And I smell like a yak
- 'Cause I don't use soap
- I'm a Viking through and through!
- Jay Baruchel as Hiccup Horrendous Haddock III
- America Ferrera as Astrid Hofferson
- Nolan North as Stoick the Vast
- Chris Edgerly as Gobber the Belch
- Christopher Mintz-Plasse as Fishlegs Ingerman
- Andree Vermeulen as Ruffnut Thorston
- T.J. Miller as Tuffnut Thorston
- Zack Pearlman as Snotlout Jorgenson
- Tom Kenny as Silent Sven