During the reign of the Vikings, Kainan, a man from a far-off world, crash lands on Earth, bringing with him an alien predator known as the Moorwen. Though both man and monster are seeking revenge for violence committed against them, Kainan leads the alliance to kill the Moorwen by fusing his advanced technology with the Viking's Iron Age weaponry.
In 709 A.D., in the Iron Age, a spacecraft crashes in the Viking kingdom of Herot, Norway, and the pilot Kainan (Jim Caviezel) survives. He turns the beacon on; learns the language and culture of the planet using a machine; and finds that the predator, Moorwen, that he was transporting, had escaped. While chasing the alien monster, he finds a village completely destroyed and is arrested by the warrior Wulfric (Jack Huston), believing that he killed the locals. Kainan is brought to Herot as a prisoner.—Claudio Carvalho, Rio de Janeiro, Brazil
A spacecraft crashes in a lake in Vendel-era Scandinavia (550-790). The only surviving occupant - a humanoid alien - retrieves a distress beacon and a computer which explains that he is on Earth, a "seed" colony that his people have abandoned. The computer downloads the local Norse language and culture directly into his brain.The spaceman soon finds a recently destroyed village.
From the wreckage emerges Kainan, a soldier from a faraway planet, and a deadly alien stowaway called a Moorwen. Before he has a chance to track down the alien, Kainan (Jim Caviezel), the Outlander, is captured by a Viking warrior named Wulfric (Jack Huston) and held prisoner in the local village led by King Rothgar (John Hurt).Freya is Rothgar's daughter and wants her to marry Wulfric. Freya refuses and says that Wulfric will be a tyrant just like his father.
Hrothgar is concerned that Gunnar, chieftain of the destroyed village, will assume it was Wulfric's doing, as Wulfric's father (Hrothgar's predecessor) had been allegedly killed by Gunnar. Wulfric interrogates the "outlander", who identifies himself as Kainan, claiming he is from the north, and states that he is hunting a dragon.The village is attacked that night by an unseen creature, which kills several men. Kainan identifies it as a "Moorwen", a predatory creature which caused his ship to crash and now will hunt men and animals alike. When Kainan is taken with a hunting party to find the Moorwen, he kills a gigantic bear that had slain some of the hunters, proving himself to the others who begin treating him as a part of their tribe.
As the Moorwen "Dragon" ravages the Viking lands, killing everything in its path, Kainan forms an alliance with the primitive but fierce warriors. Shortly after Kainan crash landed, it was the Moorwen who devastated the rival village, triggering war, with its surviving warriors led by King Gunnar (Ron Perlman).King Gunnar assaults Kainan's village, but his forces are repulsed. The enemy Vikings retreat into the forest, the Moorwen strikes, leaving the Vikings no choice but to run back to their former foes for refuge.
Gradually, as the Vikings come round to believing his story about "hunting a Dragon", and after he saves the King's life, he is accepted into their society. Flashbacks reveal his history where man and monster both seek revenge for violence committed against them: Freya (Rothgar's daughter) becomes increasingly attracted to Kainan. He explains to her the Moorwen's origin-Kainan's people invaded its land (planet), slaughtered it in the billions and built a colony there. This Moorwen, now the last of its kind, massacred everyone in the colony, including Kainan's wife and child. When his "ship" returned to the colony, the Moorwen secretly came on-board and later caused the crash. After listening to Kainan's tale, Freya gives him a family sword, saying she was told that she would know what man to give it to.
Together, the two sides attempt to destroy the Moorwen and its newly spawned offspring. Kainan devises a plan to build a huge pit just inside the village entrance, fill it with whale oil and leave wooden shields floating on the surface.Moorwen falls into the pit, and the oil is set on fire. The Moorwen bursts out, kills several people, then escapes. Meanwhile, an offspring of the Moorwen sneaks into the hall where the women and children are hiding. Erik (Bailey Maughan), the orphaned boy that Kainan has begun looking after, alerts Hrothgar, who is killed as the women and children escape.
The village takes massive casualties, including both of the tribal kings. With the warriors demoralized, most of the Vikings leave the village in search of a new home and safety.
Kainan, his friends, and the King's feisty daughter Freya (Sophia Myles), stand together to destroy the Moorwen. Kainan assists the Vikings by salvaging pieces of his crashed spacecraft allowing the forging of weapons capable of harming the creature. While Kainan is underwater, the young Moorwen attacks the boat, taking Freya. Kainan and Wulfric return to the village, where the fragments are soon forged into weapons before descending into the Moorwens' lair.
After a harrowing journey, the Vikings and Kainan confront the Moorwen in caves under the village. A young Moorwen moves toward Freya, it is distracted by the sound of Kainan's hunting party. Many of the hunters are killed, but the young Moorwen is blinded by Boromir. When it returns to attack Freya, Kainan and Wulfric pass her one of the new swords, with which she slays the young Moorwen. The cave exits to a high waterfall, where the adult Moorwen attacks. It seriously wounds Wulfric before Kainan engages it in battle. When Freya joins in, Kainan is able to knock the Moorwen over the cliff's edge to its death. Freya and Kainan return to Wulfric's side, where he passes the kingship to Kainan just before he dies.
The emergency beacon is beeping signaling that Kainan's people are coming to pick him up. As he looks up he sees the Spacecraft entering the Atmosphere. Even though this was his only chance to get home, Kainan destroys the beacon so he can remain on Earth instead of going home. He gives a Viking departure to the dead Rothgar and Wulfric, marries Freya and becomes the new King of the tribe.
