This final pre-Code issue is virtually indistinguishable in content from the issues that follow. DC had purposely homogenized itself so much since the fight against comic books had begun in the late forties that the Code wasn't really necessary.
Curt Swan and Ray Burnley turn in a nice cover here but it literally only refers--and then not accurately-to a single story panel.
Giant frog alien. Turns out he can fur himself into a duplicate of anyone or anything.
This isn't actually the alien, just a bad guy in a frog suit for reasons that make no sense.
But Bats DOES encounter the alien and the alien LIKES him!
So Batman calls Superman with the Super-Signal from the cover.
But the frog alien duplicates him AND his powers.
Although Superman had more experience with aliens, it's Batman that figures out the secret...
...which leads to a happy ending which possibly inspired the later villain, The Composite Superman.