Two years have passed since the defeat of Ultron in the battle of Sokovia. Thor has been imprisoned by the fire demon Surtur. While in captivity, the demon reveals that Odin is no longer on Asgard and the realm will soon be destroyed following an event known as the Twilight of the Gods – Ragnarök. Just when Surtur unites his crown with the Eternal Flame burning in Odin’s vault, Thor frees himself. He then battles Surtur’s forces and seizes the demon’s crown. Though he believes he prevented Ragnarök, the battle has only just begun.
In the distant past, Bor, the father of Odin, faced off against Malekith. The leader of the Dark Elves sought to unleash a weapon called the Aether on the Nine Realms before Bor handed him a crushing defeat. Following his victory, Bor secured the Aether in a stone column, though Malekith and a portion of his forces manage to escape.
It is now the year 2013 and Loki, the adopted son of Odin, stands trial for instigating a coordinated attack with the Chitauri in New York City one year prior. Meanwhile, the Bifröst has been recently reconstructed, causing no shortage of turmoil in the Nine Realms. Thor, along with Frandral, Volstagg, and Sif, repel an invading army on Vanaheim. After achieving victory, Thor and his comrades learn of the Convergence – a rare event in which the Nine Realms align. This causes interdimensional portals to appear at random. One such portal happens to be in London, England on Earth, drawing the attention of Dr. Jane Foster.
In the year 965 A.D., a fierce battle was waged between Odin, the king of Asgard, and the Frost Giants of Jotunheim. The Frost Giants’ leader, Laufey, would stop at nothing to conquer the nine realms, intending to start with Earth. Before his ambitions came to pass, the Asgardian warriors defeated the Frost Giants in in Tønsberg, Norway. In doing so, they seized the source of the Frost Giants’ power: the Casket of Ancient Winters. It is now the year 2011 and Odin’s son, Thor is prepared to ascend to the throne of Asgard. However, after hearing about the Frost Giants’ desire to reclaim the Casket, he, without Odin’s knowledge, travels to Jotunheim to confront Laufey. Assisting him are his brother, Loki, childhood friend, Sif, and the Warriors Three: Fandral, Volstagg, and Hogun. Though he is doubtlessly brave for his efforts, Thor may suffer a dire consequence for his rash actions.
Nick Fury, the director of espionage agency S.H.I.E.L.D., along with his lieutenant Maria Hill, arrive at a remote research facility. There, Dr. Erik Selvig is leading an investigation on an object of great power known as the Tesseract. Agent Phil Coulson explains to them that it has been radiating a strange energy as of late. The Tesseract suddenly opens a wormhole from which a being of unknown origin emerges. He identifies himself as Loki, the Asgardian god of deceit and trickery from Norse mythology. Arriving to subjugate the planet Earth and the humans who dwell upon it, Loki seizes the Tesseract and uses his scepter to enslave Dr. Selvig and various agents, including the expert marksman Clint Barton. Realizing the threat Loki poses, Fury activates a defense plan seventeen years in the making: the Avengers Initiative.