A silly story in which Simon Williams gets his big break playing an orange monster in a new show called Monster Man, Thing gets mad because he feels like it makes fun of him, shows up on the set, and then the set is invaded by an interdimensional demon who makes Thing fight giant vegetables.
Before the silliness starts, we see Simon Williams training in Avengers Mansion with Beast in the nice little sequence above.
The villain is Xemnu, a Golden Age monster who later appeared in a few Defenders issues. He kinda keeps lurking around. He likes to should his own name.