This comic featured two new Captain Marvel stories and one golden-age adventure featuring the world's mightiest mortal! The comic cover features Billy Batson in front of some fun-house mirrors - with Captain Marvel's image reflecting back! A similar cover was used in Captain Marvel Adventures #45. (I wrote a brief article about that which you can read here.)
The first storys is "IBAC the Cursed!" The front page tells us, "Out of the past comes one of Captain Marvel's deadliest foes, a hate-filled villain as bad as the world's mightiest mortal is good!" IBAC was one of Cap's golden age villains, making his debut in Captain Marvel Adventures #8 (1942) in the story "Captain Marvel and the Curse of IBAC!" Here, in Shazam! #4, IBAC makes a come-back!
The second new Captain Marvel story is "The Mirrors that Predicted the Future." Billy is bummed out that it appears his friends have forgotten his birthday. I wrote a separate article about that which you can read here.
The final story is a reprint of Cap's golden age adventure, "The Ownerless Diamond" which was first published in Captain Marvel Adventures #97 (1949).
There is also a full page of "Shazamail" with letters from fans. Interestingly, there are letters from two people that wrote Captain Marvel stories from Cap's golden age: Otto Binder and Manly Wade Wellman.