Thor (1966 series) #163

Meanwhile, Thor is pulled into the funnel by a Mutate army, whose leader has Sif held captive with attracto-spheres. Thor rescues Sif and finds the world they're in is a post-atomic war holocaust, a glimpse into humanity's future. They find the Atomic Research Center and, approaching it, discover Pluto who tells Thor he captured Sif in order to lure him there.

Thor attacks but the Mutates fire weapons that knock him and Sif out. They beg Pluto for the opportunity to attack the 20th Century to gain new human slaves.

Meanwhile, within the Research Center, a metal cask's lid opens to reveal a human-shaped cocoon.