Synopsis: A professor comes to Jimmy Olsen with a Norse tablet telling him that whoever reads the last line will disappear. He wants Superman to destroy it, but Jimmy becomes curious and does the translation at the public library. Using viking gear borrowed from a movie studio, Lois helps him into a lake with a viking ship, where he uses the Norse he has learned to read the last line, and disappears.
He arrives in the Norse lands and rescues Thor from a binding that Loki has put him in. Jimmy says he is glad he picked up enough Norse from his recent study to communicate. Thor introduces Jimmy to his parents, Odin and Frigga, then gives him a horn to summon him any time he has need, just like Superman.
Loki causes trouble for both of them, while Jimmy sets down stories of the Norse people and gods to be remembered for all time.
Jimmy initially sees Loki as a rival to Thor comparable to Lex Luthor for Superman. Ultimately, though, he concludes that Loki is ancestor to Mr. Myxzptlk, so he shows him a dime, a penny, and a nickel. He asks him which one he would like to change to bear his face, and Loki answers "the nickel," because it's the largest, which causes him to disappear.
Jimmy then asks Thor to hurl him through the time barrier to his own time, which he does, meeting Lois at the lake and telling her he now has super-friends in both eras.