The Riders are playing a game they call Beat the Dome. Hiccup successfully wins. It is Snotlout's turn, he rides on Hookfang then flies through the forest. After they fly past the forest they go underground, then finally are at the dome. However, they are not fast enough and eventually they crash. The Riders check on Snotlout. He says he is fine, but Hookfang is suddenly gone, then Snotlouts begins searching for him.
Hours have passed, but he is unable to find Hookfang. Hookfang insists on staying and tries to scare off his Rider by igniting his body, however Snotlout persuades him and he eventually agrees. The two head back to base. It is feeding time for the dragons, while Hookfang gets his favorite fish, but he rejects it and throw it back at Snotlout. Hiccup tells Snotlout to lock him up in his pen so he will behave. Snotlout agrees. He escorts Hookfang to his pen, saying "see you in the morning" and leaves to go to bed.
Morning has come, Snotlout has a big bass for Hookfang, and goes to his pen, to find that Hookfang broken out. The other Riders help Snotlout find Hookfang. They eventually find him in the same cave he was when he disappeared the day before. They approach him, but suddenly another Monstrous Nightmare shows up. They identify it as a female. And that explains why Hookfang disappeared twice, because he was attracted by the female.
Snotlout tries to get on his back and tells him that he can visit her another day but before he can reach any further he blasts him with his fire. Then the other Riders carry Snotlout and return to Dragons Edge. They discuss Hookfang's current behavior and they figure it out (or so they think). Hookfang is going feral.
Snotlout tells them he will get him to come back. He plans to scare off the female by throwing an electric eel, but Hookfang arrives and toss it back at his owner. Snotlout then says "I've had enough of you Hookfang, it's time to choose her or me." Hookfang sadly chooses his female mate, and, sad because of his decision, Snotlout leaves. He then returns to base and inform his fellow Riders on Hookfang's recent behavior. He tells them that he will just let it be for a while and goes to sleep.
The next morning Hiccup gathers 3 Monstrous Nightmares to replace Hookfang, but Snotlout doesn't like any of them. He tells the Riders that he will quit. Shocked, the Riders try to persuade him not to quit, but Snotlout says that if he can't fly Hookfang, he doesn't want to fly any dragon. So Snotlout tells them that he will say farewell to his dragon and sail back to Berk.
He arrives at the cave to see Hookfang injured. He suspects that the female is the one responsible for it and pulls out a sword and points it at her. Later on a fight breaks out. Snotlout and the female violently charge at each other, but before any of them can land a blow Hookfang intercepts them. They show Snotlout some eggs. Snotlout then is frightened, and suddenly a Titan Wing Monstrous Nightmare appears and wants to destroy the eggs. Hookfang tries to stop him but is overpowered and thrown back. Snotlout tries to fight off the enemy dragon with his sword, but Hiccup and the other Riders come to the rescue. The Titan Wing retreats.
They ask Snotlout what is going on, then Fishlegs figures out that it was not a mating call Hookfang was answering, it was a distress call, explaining that Hookfang is willing to risk his life to protect the eggs from the Titan Wing. The Titan Wing comes back, ready to engage in battle. Snotlout requests the Riders to leave the fight to him and Hookfang.
The two fly into the air to battle the Titan Wing. No matter what the Titan Wing does, Hookfang and Snotlout keep on dodging every attack he makes, a few minutes later they come up with a plan; play beat the dome. The Riders then activate the dome. Snotlout and his dragon then fly to the underground part of the dome to contain the enemy Titan wing, but they don't quite make it. However Snotlout's plan was to contain them both in the dome. (due to the smaller size of Hookfang, they have the advantage.) Hookfang rapidly fires at the big dragon.
The Riders outside are wondering who is winning, then they hear Snotlout saying to open the dome. Once they open the dome they see the Titan Wing, but he collapsed, and find Snotlout and Hookfang standing behind the enemy Titan Wing dragon, leaving Snotlout and Hookfang victorious in the battle. Hookfang then tells the Titan Wing to leave before he gets hurt further, the Titan Wing accepts his request, apologizes to Hookfang, then leaves. Back at the cave they find the eggs have hatched. Snotlout and Hookfang are together and happy again.
- Second time Snotlout mimics Hiccup. (When Darkness Falls)
- Female Monstrous Nightmares are able to send a distress call for non-mated male Monstrous Nightmares for help to defend their eggs.
- Snotlout almost gives up being a Dragon Rider in exchange for Hookfang being happy and being free.
- Once again, the twins show a higher level of intelligence, this time with a greater knowledge of theatre.
- Ruffnut stated that she heard that male vikings fight for female viking but she's never seen it.
- This is the first episode where a Titan Wing dragon can be seen.
- Jay Baruchel as Hiccup Horrendous Haddock III
- America Ferrera as Astrid Hofferson
- Christopher Mintz-Plasse as Fishlegs Ingerman
- Andree Vermeulen as Ruffnut Thorston
- T.J. Miller as Tuffnut Thorston
- Zack Pearlman as Snotlout Jorgenson
- Barf and Belch
- Female Monstrous Nightmare
- TItan Wing Monstrous Nightmare