The cover of Shazam! #1 featured Superman, Billy Batson and Captain Marvel on the cover with words stating "Billy Batson say the magic word...and become the World's Mightiest Mortal!" Across the top of the cover you read "With one magic word...Shazam!...The Original Captain Marvel.
The first story is entitled "In the Beginning" and is a "retelling of the greatest legend in comics." It gives readers the origin story of how Billy Batson met the wizard Shazam and was given the power to transform into Captain Marvel, the world's mightiest mortal, by saying the magic word, "Shazam!"
The second story is "The World's Wickedest Plan!" and is the very first adventure of Captain Marvel since the golden age of comics! And who is the nemesis for this new adventure? None other than Dr. Sivana! The story also explains how Captain Marvel and friends were captured by Sivana and held in suspended animation for over 20 years.
There is a brief article entitled "Shazam and Son" by E. Nelson Bridwell that gives an overview of Captain Marvel's comic history and a brief bio of some of his friends that were held in suspended animation along with him.
The final story of the comic is "The Endless String." It is a reprint from Captain Marvel Adventures #55 (first published on March 1, 1946*).
This is a great comic that introduced Captain Marvel to comic readers that may have never heard of him and it reintroduced Cap to fans that hadn't seen him in action for over 20 years! It bridges the gap from Captain Marvels golden age adventures and launches him into new adventures in the 1970s.
*According to Mike's Amazing World of Comics