A Viking boy called
Hiccup introduces his village of Berk ("it's been here for seven
generations, but every single building is new"). The village is attacked
by dragons, who steal food (mostly sheep) and set things on fire (hence all the
new buildings). The villagers grab weapons and try to fight the dragons off.
Despite being told by every adult in sight to go indoors, Hiccup hauls out a
bolas-shooting cannon he made himself and shoots a dragon out of the night sky.
(As assistant to the village blacksmith, Gobber), Hiccup has access to tools
and materials and knows how to use them.) The dragon lands in the woods some
distance form the village and no one believes that he hit anything, so it's the
next day before Hiccup can go looking for it. It turns out to be a rare and
deadly Night Fury, but Hiccup can't make himself kill it. Instead he releases
it -- whereupon it also refrains from killing Hiccup – and it flies off through
the trees.
Hiccup discovers that
the dragon (which he eventually calls Toothless because of its retractable
teeth) has holed up in a steep-sided valley because it can no longer fly more
than a few feet at a time. While sketching the dragon, Hiccup realizes that
it's missing a tail fin. He makes a prosthetic tail fin out of leather. The new
fin helps, but Toothless can't control it and inadvertently takes Hiccup for a
ride, giving him a clear idea of what's needed to help the dragon fly right. In
a series of workshop and test flight scenes, Hiccup builds and perfects a
saddle, a control mechanism for the tail fin, and a safety harness.
Meanwhile, Hiccup's
father Stoick has signed him up for dragon training with Gobber, which is very
different from the training he's already doing with Toothless: he's going to
learn to fight dragons. At first, he's the worst student in the class. Since
Hiccup has always been an accident-prone klutz, this comes as no surprise to
his classmates Astrid, Snotlout, Fishlegs, Ruffnut, and her twin brother
Tuffnut. (Hiccup's a little sweet on Astrid.) Before long, Hiccup is able to
use some things he's learned while working with Toothless to soothe and manage
the school's practice dragons. (It turns out dragons are just big kitty-cats:
they like to be petted, there's a kind of grass that's like cat-nip to them,
and they love fish (but hate eels).) When Stoick returns from a failed search
for the fabled nest of the dragons, he's surprised but thrilled to hear that
his son is doing brilliantly at dragon training. He gives Hiccup a horned
helmet made from one of his dead mother's breastplates. But Hiccup, as usual,
is unable to get around his father's expectations and speak frankly, so he
can't explain that his success at dragon school is unlikely to lead to the
slaying of any dragons.
When Hiccup subdues a
practice dragon, unintentionally earning the privilege of killing it before the
entire village, he's horrified and decides to flee with Toothless. However
Astrid, having noticed Hiccup's frequent disappearances and secretive behavior,
is suspicious. She follows him to the hidden valley and sees Toothless. Unable
to explain his relationship with the dragon, Hiccup takes her flying, and she's
captivated. But they get caught up in a flock of dragons returning to their
nest carrying food. The dragons fly inside a mountainous island and drop the
food into a pit, which turns out to contain a huge, terrifying, and very hungry
dragon that eats the smaller ones if they don't bring it enough food. Hiccup
and Astrid and shocked to realize that the dragons have been stealing their sheep
to keep from being eaten themselves. When they get home, Hiccup convinces
Astrid not to reveal the location of the dragon nest. Before she goes, she
punches him in the arm and says "That's for kidnapping me." Then she
kisses him and says "That's for everything else."
Everything goes wrong
at the dragon-killing ceremony. Hiccup discards his weapons in an attempt to
show the Vikings that dragons only fight to defend themselves, but Stoick and
others intervene and the dragon attacks. Toothless comes to the rescue and is
on the verge of killing Stoick when Hiccup calls Toothless off. Despite
Hiccup's protests, the angry Vikings chain Toothless up. When he ineptly tries
to explain, Hiccup lets it slip that Toothless took him to the nest of the
dragons, and Stoick resolves to use Toothless to find the nest again. He won't
listen to Hiccup's warnings about the giant dragon. He loads Toothless on his
ship and the Viking fleet sails off with all the warriors in the village,
disowning Hiccup and leaving him behind. When Hiccup wonders aloud why he
didn't kill Toothless when he had the chance since it would have avoided all of
this, Astrid challenges him to explain why. In doing so, Hiccup comes to an
epiphany about his moral character, his personal strength and Astrid's faith in
him. Inspired, Hiccup and his classmates mount the practice dragons and fly off
in pursuit of the fleet.
At the dragons'
island, the Vikings use catapults to break open the side of the mountain in
which the giant dragon is trapped. When it comes out, Stoick realizes that he's
made a mistake. He resolves to fight it himself to buy the other Vikings time
to escape; Gobber volunteers to join him. While Stoick and Gobber prepare to
sacrifice themselves to distract the dragon, the kids arrive to join the
battle. They do manage to distract the giant dragon a little, but it sets the
Vikings' ships on fire. While his comrades keep the giant dragon occupied,
Hiccup tries to rescue Toothless (who's still in chains) from the burning ship,
but they end up under water and Stoick rescues both of them. Then Toothless and
Hiccup go after the giant dragon together. They draw it up into the clouds and
away from the Vikings, trying to get it to crash on the island. In the end
Toothless releases a blast into the giant dragon's open mouth and it crashes
and burns, apparently taking our heroes down with it -- we see Hiccup fall
toward the fire as Toothless tries desperately to catch him. On the ground, a
heartbroken Stoick approaches the wounded Toothless wondering what has become
of his son; Toothless opens his wings to show that he saved Hiccup.
("Well, most of him," Gobber remarks cryptically.)
Back at home, Hiccup
wakes up and Toothless urges him out of bed. Hiccup finds that he lost his left
foot in the battle with the giant dragon. However, Gobber has made him a new
one, ingeniously spring-loaded. (Hiccup and Toothless now have matching
disabilities.) They go out into the village, which is full of swooping,
frolicking dragons; the Vikings now treat them as pets. Astrid greets Hiccup
with a kiss. Supplied by Gobber with a new tail fin prosthetic and saddle for
Toothless, Hiccup takes flight with Astrid and his friends as he exults at the
new alliance of Vikings and Dragons.
