Reunited with his long-lost love Sif, Thor spends time with her as they compete in a friendly spearing game. Their fun is interrupted when the couple is attacked by an army of Rock Trolls, who seek to capture the two as they are trespassing on Rock Troll ground. The Rock Trolls manage to capture Sif and carry her away but have less luck subduing Thor. Thor manages to fight off their best efforts to subdue him, sending them fleeing. The Thunder God follows not far behind, hoping to save Sif from danger. Following the Trolls down into their cavern home, he is confronted by the Troll's greatest warrior: Ulik.

While elsewhere in the caverns, Sif is brought before Geirrodur, the leader of the Rock Trolls. Geirrodur decides that Sif would make an ideal means of defeating Thor and plots to use her to steal Thor's hammer. Aware of the Thunder God's double identity, he plots to steal the hammer when Thor next changes into his mortal guise of Donald Blake. To facilitate this, Geirrodur uses "Vapours of Quietude" on Sif, knocking her unconscious, and has his mend toss her down a secret tunnel that will send her to Earth.

Elsewhere, Thor and Ulik's battle rages on, and the two find that they are equally matched in battle. However, as the battle rages on, Ulik becomes angrier and angrier and soon goes into a berserker rage, gaining the upper hand against Thor. Before Ulik can best Thor in combat, he is suddenly teleported away. Thinking it was his father Odin who aided, Thor is corrected by the appearance of Geirrodur, who tells Thor that he has transported Ulik to Earth to keep Sif hostage and tells Thor that should he go after his true love, the Rock Trolls will invade Asgard.

Thor teleports to Earth to save Sif, not wishing to sacrifice her, just as Geirrodur had planned. With Thor gone, the Rock Trolls begin their invasion of Asgard, sending the sum of their attack forces against the Golden Realm. While on Earth, Thor appears, vowing to stop Ulik and save his true love.

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