The Escape from Muspelheim was a successful escape attempt orchestrated by Thor after extracting information about Ragnarök from the fire demon Surtur.
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.
Thor said that sometimes you have to get captured to get a straight answer out of someone with that someone being Surtur.
Thor managed 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.
Surtur announced that Ragnarök 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.