Batman spots an old man in trouble in Gotham City. He swoops down to help, only to realize the three suited men aren't the famiilar thugs he expected, but nightmarish monsters. The old man insists he is fine on his own and needs no help and walks off. After getting away from the monsters, Batman follows the old man.
The old man goes down into Gotham's subway system, trying to find a trigger rock. The pursuing monsters follow. The old man, since Batman is persistent about following him and getting an explanation for the weirdness in his city, conjures a magical image Flashback explaining how he got where he is now.
- Old man: And I won't repeat myself, so pay attention.
It turns out that the old man is an ancient wizard and was sitting on his throne minding his own business when Black Adam showed up out of nowhere to threaten him. The wizard simply summons his champion, little Billy Batson. The wizard tells the kid to say his name so he can power up and dispatch the interloper.
Billy does so, saying the magic word: SHAZAM!
But Black Adam is prepared for this. He tosses up some sort of device that catches the lightning and traps it. Billy can't turn into Captain Marvel. The wizard, revealed as Shazam himself, can't do anything either. Adam sets monsters on the wizard and magically places Billy in shackles. The last thing the wizard says is that his powers grow weaker the longer he's away from his throne, and that he must hurry before they're gone altogether.
Now having finished his explanation, Shazam goes back to searching for his Secret Passage trigger. Batman discovers the monsters have pursued, and backs away from them knowing they outgun him. He manages to step through the trigger brick into a portal in magical space that has them several hundred yards away from the Rock of Ages. Shazam grumbles about having missed his target; Batman simply uses his grappling hook gun to tow them into the rock.
Adam is watching in a scrying pool as the monsters he released from the Rock arrive on earth and begin causing trouble. Billy spots Batman and the wizard, and starts trash talking Adam to distract him from their sneaking approach.
Shazam attempts magic to set things right but has been too far from his throne for too long and is powerless now. Instead, he tells Bill—>y that he has the power to free himself if he concentrates. Billy, astonished, asks if the wizard really thinks he can do it. Shazam admits he is developing more confidence in mortals lately.
With this vote of confidence, Billy gives it another try:
- Billy: Shazam! [louder and with more determination] SHAZAM! [louder and with all the determination a little kid can muster] SHAZAM!
The imprisonment sphere breaks, and lightning strikes, turning Billy Batson into Captain Marvel. The fight is pretty quickly won as Adam leapt from the throne in disbelief and Shazam immediately took his seat back.
A furious Adam tries one more time to attack the wizard, but Shazam banishes him so far away that it should take centuries to get back. He then advises Captain Marvel to go back to earth and mop up the creatures Adam has set loose on the mortal world.
- I Shall Taunt You: Billy pulls this on Black Adam to distract him.
- Luck-Based Search Technique: Batman stumbles upon the trigger stone while Shazam searches more systematically. Played for Laughs in that Shazam can't remember which specific rock because it's been millennia since he's had to use it.
