Lois Lane tries to find out who was responsible for a recent attempt
on Superman's life, but doesn't get very far and is extremely irritated
by the fact that Superman is shadowing her to ensure her safety. When
the two have talked about this, Superman flies off to deal with some
trouble elsewhere.

The problem Superman must deal with is the two junior members of the Marvel Family, Mary Marvel and Captain Marvel, Jr.,
who are acting very erratic in central Metropolis. Mary is acting
rather bizarrely, spouting absolute gibberish, and Captain Marvel, Jr.
is experiencing an overload of the speed of Mercury, with which Superman
is barely able to keep up. It transpires that the three Marvel Family
members were converted to their super-powered state involuntarily, with
their powers gone absolutely crazy, particularly Captain Marvel
himself, who is left as just a mouth repeating Superman's name over and
over again. The three of them then fly to Fawcett City where there is a
giant frog causing trouble.

Back in Metropolis, Lois Lane breaks into a warehouse, still on
her lead. When she turns around, she discovers four security droids.

Meanwhile, Superman and the Marvel Family battled the giant frog.
When Superman pulls on the tongue, the frog just splits into smaller
ones. Then Mary is cut in half by the frog's huge tongue. As the
situation worsens, Superman thinks through and soon figures out that
Captain Marvel needs to use his body, as his Kryptonian nature seems to
make him invulnerable to the giant frog. Holding onto Captain Marvel's
mouth and chin Superman shouts "Shazam", and becomes Captain Marvel.
Superman/Captain Marvel fly into the frog's mouth and into a hidden
world. There he comes face to face with a frog deity, which is actually a
sort of god called Heqt. Through using the Wisdom of Solomon,
Superman/Captain Marvel learns from Heqt that he is protesting at the
way frogs and other amphibians are abused by human science.
Superman/Captain Marvel is able to reason with Heqt and persuade her not
to cause more trouble, something Superman acknowledges he would never
have been able to do.

The incident reaffirms the bond of friendship between Superman
and Captain Marvel, and also reminds Superman not to underestimate
others' abilities, whether they are a fellow hero or his wife.

Back home, Lois comes in to find Clark sitting down reading "The
Frog Princess". She explains that her ordeal in the warehouse lead to
her being chased through the sewers and winding up in Suicide Slum. The couple makes up with a kiss.