The dragon riders discover a lush island that turns out to be the home of the Deathsong, a massive, never-before-seen dragon that threatens to trap them forever. 
- The dragon riders leave Berk to explore beyond the archipelago with the Dragon Eye.
- The Death Song is introduced.
After Hiccup shows the Dragon Eye's mechanism to the Riders that projects maps, new info about dragons and language they can't even understand, Astrid asks what's their next move. Hiccup then shows the Dragon Eye for the Council to see at the Great Hall, where Hiccup informs them that the maps that it projects goes beyond the boundaries of their archipelago, and asks the Council to be in favor to explore these, as proof that there is another world out there.
However, council member, Spitelout Jorgenson is reluctant as he expresses his concern that he claims that looking for other lands may end up looking for trouble and shatter the period of peace, that's been going on for three years since their last encounter with the Berserkers, making it Berk's best and longest time of peace. Council member, Sven is also in favor, saying that no good will come out of discovering new unknown lands and wild dragons. Spitelout also adds that they should be instead hunting down Dagur and his men. Hiccup tries to justify that Dagur is now venturing out beyond their borders, with the help of the Dragon Eye they can navigate him and take him down.
Stoick steps in to put the meeting to a conclusion, by saying that Spitelout's concerns and demands are legitimate, and that their three years of peace is important and should go on that way, disappointing Hiccup. But Stoick then points out that if one important thing in the world for them is out there, he asks how far they would be willing to go to get it. By this, Stoick favors Hiccup's enthusiasm and eagerness to explore more dragons as that is his purpose, and asks the Council to at least support him. Stoick lets Hiccup and Toothless go to find whatever is out there pulling him, and when he does Stoick assures him that Berk will be waiting for it. Hiccup proudly sets off with their journey.
When Hiccup prepares to fly off, he is surprised that the Riders have decided to go with him in his long quest to search for more new lands and dragons, as they all exclaim to head forth to 'the Great Beyond'. Hours later, most of them are exhausted as they've been flying almost all day, Hiccup tries to cheer their spirits up but they find themselves in the center of a brutal lightning storm. The Riders suggest they head back, but Hiccup tells them they've come too far to turn around.
They spot an exit, and heads through it to escape the storm. When they emerged, they stumble upon to their first stop and find incredible and magnificent islands. But Fishlegs suggests they cheer about it later as their dragons need rest, suddenly a soft and melodious music is heard that causes their dragons somewhat, obsessed to it. They're being drawn into an island where the source of the music is heard and they decide to rest there. When they land, the Riders and their dragons enjoy their time there with it's amazing lakes and valleys, while the mysterious song still continues to play.
Finding the island to be paradise, they decide to set up camp for the night, Snotlout takes care of setting up the fire by introducing Hookfang's Monstrous Nightmare gel, that when incinerated, the gel bursts into flames, easily creating fire. At night, most of the Riders are asleep, Hiccup and Astrid stay awake for a while discussing how their first new discovered island is beautiful and is in favor of Hiccup's ambitions of other worlds of dragons out there. The next day, Hiccup wakes up Astrid early as Hiccup becomes suspicious that the mysterious music they heard has suddenly stop, but they have a bigger problem, they find their dragons gone.
They've searched for hours and find no clues to where they've gone to. But luckily, Toothless returns and is glad to see his Rider, but goes mad trying to tell them something about their dragons. Toothless grabs hold of Hiccup's prosthetic leg with his mouth to drag him somewhere, unbeknownst to Toothless, he just literally takes Hiccup's prosthetic leg, he finally realizes it and apologizes. Hiccup and Toothless decide they fly off throughout the island to search for their dragons while the rest of the Riders stay behind in case they return.
But almost immediately, trouble ensues as Hiccup spots a wild Thunderdrum heading towards the Riders. Hiccup and Toothless heads back to help them, but Toothless suddenly resists as he again becomes attracted to the mysterious music that's picking up volume. Hiccup eventually tells Toothless to head back and defend the Riders, however, the Wild Thunderdrum releases a deafening blast against them, but fortunately Hiccup and Toothless draws it away. When Hiccup checks on them, the Riders can barely hear themselves after the attack, so they communicate to Hiccup with their complains loudly, demanding Hiccup that they search for their dragons on foot altogether, Hiccup shouts frustratingly he agrees.
As they venture through the island deeper to the source of the song, the area becomes suddenly dark and creepy. They even stumble upon a huge pile of dragon bones and a small unknown hard substance, they then hear dragons in distress and hurries to check it out. When they find it, they find lots of dragons (including their's) immobilized by being smeared by a hard amber-like substance, Fishlegs theorizes that something is trapping them and then plans to break them out and eat them, Ruffnut asks who could do such a thing. Suddenly, a large mysterious dragon appears who is responsible of trapping the dragons and luring them with it's song, the Riders hide and luckily the dragon doesn't stay long as it grab it's next meal and leaves.
Hiccup is surprised, to see Fishlegs decide to name the dragon first, he suggests it'll be called 'Songwing', but Tuffnut has a better one 'Death Song' which Hiccup sees as legit. But Astrid tells them now is not the time as they need to find their dragons and free them. However, the Death Song returns and Toothless immediately attempts to fight it, but proves no match when he gets spewed by the hardening substance and is trap also. Hiccup orders the Riders to hurriedly free their dragons, but this makes them easy targets for the Death Song, who it easily spews them with the substance and gets trapped. Hiccup is pushed out of the Death Song's sights by Astrid and she gets smeared with the substance instead. Hiccup has to flee and abandon the Riders and their dragons, he slips into a slide-shape rock formation and gets transported somewhere out.
Unfortunately, the Wild Thunderdrum prior discovers him, and seems to get revenge on Hiccup. But instead, the Thunderdrum tackles him out of the way of the Death Song's sight, almost being spewed. The Death Song pins down the Thunderdrum, Hiccup fends it off by using his shield that burst a bolas that holds off the Death Song. Hiccup sees he has little time to do a decision, so he decides to ride the wild Thunderdrum, as a result, the Thunderdrum reacts by flying far out of the Death Song's territory. Hiccup tries to tell the Thunderdrum to settle down as it continues to fly out of control, but he realizes that Thunderdrums can barely hear themselves.
They crash, but fortunately Hiccup is alright and sees that they lost the Death Song. But begins to regret his actions of endangering the Riders' and their dragons' lives by bringing them all here, and now he frustratingly recaps that his friends are about to be eaten and he's stuck with a Wild Thunderdrum who can hardly hear a thing, but Hiccup realizes it to be an advantage against the Death Song's luring music. So he decides to train and bond with the dragon, by helping the Thunderdrum get rid of the Death Song and also rescuing the Riders and their dragons in the process. The Thunderdrum agreees and allows Hiccup to ride on him.
At the Death Song's territory, the Riders are still stuck for an hour now. Hiccup and the Thunderdrum arrives attempting to break the hard substance by ramming it, but to no avail. Hiccup comes up with an idea when he is informed by Fishlegs that once the substance cools down it hardens. Hiccup tells them to stay put and grabs Snotlout's container of Monstrous Nightmare gel and smears it all over the Riders and dragons, creating a trail when it gets ignited, thinking the burning gel will weaken the substance. Snotlout is still concerned that the smeared gel will also set them in fire, but Hiccup assures Snotlout that it'll turn out ok.
However, the Death Song arrives and grabs a Gronckle as it's next meal, Fishlegs tells Hiccup to hurry as he fears his next. Astrid calms him down claiming it'll take him over an hour to finish it, unfortunately, it took only minutes and the Death Song returns to grab Fishlegs as the main course. Hiccup and the Thunderdrum works together of drawing it away, when it gets lured into the sky, the Thunderdrum misses it and dives into the ground where Hiccup separates and jumps into the gel with his shield in the front, creating a spark as Hiccup's shield slides towards it. The gel works and frees the Riders and their dragons. Hiccup reunites with Toothless, and they prepare to fend it off as the Thunderdrum already begins it's move. Before they fly off, they notice a trapped adolescent Thunderdrum, meaning that the adult Thunderdrum is a parent and was trying to draw the Death Song away from his child so that he could rescue the young Thunderdrum. Hiccup assigns Snotlout to free it.
Hiccup and Toothless lures the Death Song into a cavern saying it's his 'new home'. The Death Song struggles to chase them into the small cavern due to it's size, as it gets hit by rocks along the way. When Hiccup and Toothless go for the exit, the adult Thunderdrum blasts the exit along with Toothless, and traps the Death Song, making the dragon unable to lure any dragon in with it's song. The Riders arrive at the scene along with the adolescent Thunderdrum where the adult Thunderdrum rushes to embrace his child again. Hiccup watches happily for them but advises them to look for another settlement as he fears the blocked cavern won't hold the Death Song forever, despite Tuffnut informing him that the Thunderdrums can't hear him.
When they venture out, Hiccup apologizes of bringing them with him after what happened, and he asks if the Riders has any plans of turning back. But to his surprise, the Riders take it as a joke as they wholeheartedly refuse to turn back saying it's the most fun experience they had after three years. They then suggests they find an island for their own, to act as their base of operations as they're too far out from Berk. Hiccup gives Snotlout full authority of picking an island that's suitable for them after bringing the Monstrous Nightmare gel that inadvertently save their lives.
For Snotlout, it's a great honor for him to pick an island and he and Hookfang take the lead as he exclaims and the Riders also, their motto, 'Into the Great Beyond!'.
- This is the third time Valka is mentioned in series, and the first time by name. Stoick mentions how he searched for her after she was taken.
- Stoick also mentions Alvin the Treacherous, though Alvin has not made an appearance in this season thus far.
- While the Dragon Riders had no idea what the Death Song's blasts were made of, Fishlegs does call it an "amber rock" substance. Though he could have been referring to the color of it and not the actual amber.
- Thunderdrums are revealed to have poor hearing.
- When showing the other riders what the Dragon Eye can do, Hiccup tells Snotlout that Berk has no crest of their own. Yet in previously aired episodes of Dragons: Riders of Berk, the "Berk Crest" is mentioned many times, namely during the episodes "Defiant One" (Hiccup's satchel with "the Berk Crest") and "Breakneck Bog" (a chest with "the Berk Crest").
- 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 and Mulch♣
- Thomas F. Wilson as Bucket ♣
- David Tennant as Spitelout Jorgenson
- ♣ designates a character that appears but does not speak