With Heather getting more and more obsessed with finding her father, Oswald, Dagur requests Hiccup's help in tracking down a lead on his disappearance.
Tropes:
- Babies Ever After: Turns out the reason why Chicken has been acting strangely and went missing is because she found herself a fetching young rooster and now has a clutch of adorable baby chicks.
- "Be Quiet!" Nudge: Astrid elbows Snotlout quite hard because he has been doing a dramatic narration for the episode... and being rather annoying at that. He gets the message.
- Breaking the Fourth Wall: Snotlout spends the whole episode talking towards the audience, narrating the events of the B-Plot like it was a suspenseful murder mystery. Astrid doesn't find it funny.
- Continuity Nod: The giant skeleton the group see on Vanaheim is that of a long dead Bewilderbeast, though they don't know it yet...
- Dead Man Writing: Oswald left behind letters for both Dagur and Heather to find after he's gone.
- It Only Works Once: The Sentinels refuse to even allow Hiccup, Fishlegs, and Dagur to approach the island, much less enter and pull the same trick to escape, as they now know they aren't sick dragons and hence don't belong.
- More Teeth than the Osmond Family: The Grim Gnasher's main mode of offense is that they fire teeth as projectiles. Whether or not it is their own teeth or the teeth of other dragons is never given.
- The Reveal: Oswald was shipwrecked on Vanaheim, and died defending the island from predatory dragons alongside the island's Sentinels.
- Scavengers Are Scum: The Grim Gnashers are an unwelcome group of scavenger dragons that come to pick off the dead or dying dragons that have come to Vanaheim. It is only after the riders chase them off do they receive the Sentinels' respect.
- So Proud of You: Dagur grew to hate himself for using his father's disappearance to take over the tribe, but he finds out that Oswald was proud of him for taking control of the Berserkers and being the leader they needed in his absence
- Sure, Let's Go with That: When the Sentinels block them from entering, Dagur loses his patience and dives right at them, followed by Hiccup and Fishlegs. Their speed combined with the gusts of the Sentinels allow them to crash into the beach without dying. When Fishlegs points this out, Dagur just runs with it, obviously not having thought that far ahead when he did it.
- That's No Moon: It is in this episode that Hiccup and Fishlegs realize that most of the island is actually the long-dead corpse of a Bewilderbeast dragon and that Oswald was there before them.
- Tropey, Come Home: The whole B-Plot of the episode is that Chicken has gone missing and Tuffnut is in a tizzy over it, with everybody (except for Hiccup and Fishlegs, who are off helping Dagur in the main plot) helping him find her.
- What You Are in the Dark: Dagur is riddled with the guilt of abandoning his father and using his disappearance to take over the tribe, even lamenting he didn't even think to send out a search party. When the group finally locate a dwelling on Vanaheim, it takes all of his courage to open the door to his father's legacy, something the old Dagur would never have done.
