Escape from Muspelheim

The Escape from Muspelheim was a successful escape attempt orchestrated by Thor to extrapolate crucial information about the impending Ragnarök from the ruler of the Fire Demons Surtur and escaping from his Realm.

Background
Thor has been captured by mysterious enemy forces. He rambles towards a skeleton sharing his cage about seeking the Infinity Stones but having found nothing.

He says that sometimes you have to get captured to get a straight answer out of someone with that someone being Surtur. Thor manages to get freed from the cage, and arrives at Surtur's world, Muspelheim in which the latter taunts him with the knowledge that Odin is no longer on Asgard and Thor's absence leaves it vulnerable.

He announces that Ragnarok is coming to Asgard at his hand and there is nothing Thor can do to stop it, while foolishly confessing that his crown is the source of his powers.

Battle
Thor takes this big cue to call for his loyal hammer, Mjolnir, causing Surtur to call for his creatures, leading to a lengthy battle between Thor and Surtur's army.

During the battle, he was captured by Surtur in chains, but he managed to free himself easily with Mjolnir, causing Surtur to use his Twilight Sword, and Thor continued his fight against Surtur and his creatures. At the end of the battle, Thor tries to return to Asgard, Heimdall does not respond. His replacement, Skurge, only notices Thor's call when one of the women he is trying to impress points it out.

Returning to Asgard, the Fire Dragon attempted to return to the place with Thor himself and to finish the job, but Thor used the hammer to smash off the creature's head, causing its blood to be spilled on Skurge and the women.

Aftermath
To be added