-Open with Black Adam's (played by the Rock) tale of corruption
-The Wizard's disowning of Adam. (Wizard Shazam possibly played by Christopher Lloyd)
-Opening Credits
-Billy Batson's parents death (perhaps make it due to a drunk driver, or something more "real")
-Moves into uncle's house with sister.
-Billy one day tries to intervene in a mugging. He becomes bruised up by the two muggers.
-Police show up and catch one of them with a taser, but the other one gets away. The police drive Billy home and speak with his uncle.
-Billy tries to explain his actions, but is disowned by foul uncle. Billy wanders to an abandoned, mostly vacant apartment building and sleep on the floor.
-Some time passes. Billy tries to do the best he can to support himself. He gets a job at a local radio station as a junior assistant.
-One morning, he is heading out to get breakfast.
-The mugger that got away spots Billy. Billy double takes, and so does the mugger.
-Billy is chased down by the mugger.
-Billy runs down to the subway station.
-The mugger continues his chase.
-Billy turns a corner and falls down into the gap where the subway tracks are.
-Billy attempts to climb back up as he sees the lights of the train coming towards him.
-The mugger stands over the edge over the small cliff that divides the station from the tracks. As Billy lifts himself up over the ledge to safety, the mugger gives Billy a boot to the face.
-The train appears to have collided with Billy.
-Billy opens his eyes to see he is on the train.
-Everything outside the windows looks like strange.
-The train stops.
-Billy gets out to find a long, extending cave.
-This is where he meets the Wizard and is given his powers.
-The cave collapses as Billy re-enters the train.
-Billy wakes up laying on the tracks. It is as if time stood still when he was in the cave.
-He whispers "SHAZAM..."
-Lightning strikes.
-Mugger: "Holy SHIT!"
-Captain Marvel emerges from the strike.
-The mugger laughs "Who the hell are you?"
-Cap walks up to him seemingly angrily. He doesn't say a word. He then puts on
a smile. The mugger throws a punch. Cap's head only very slightly shifts to the side. He looks back at the mugger with that smile still on his face. The mugger cowers in fear and runs off. Cap (Billy) looks down at his hands and smiles. He says "SHAZAM" and turns back into Billy.
-He returns to the broken down apartment and heads to the roof. He calls out "SHAZAM". He transforms, this time, in much more glorious fashion as he rises into the sky before the zap. He hears the wizard speaking to him. Teaching him how to fly and use his capabilities.
-Billy is perplexed.
-Later, Billy decides to go find some adult clothes.
-He transforms into Cap and uses the clothes to go on a job hunt. He eventually uses this disguise to sign for a lease on an actual apartment. During this time, he goes between being Bill, stopping more petty crimes as Cap, and being an adult citizen as the street-disguised Cap. Most of these sequences would be condensed into a montage of sorts.
-At the end of the montage sequence, Billy closes his eyes for a good night's sleep.
-One of the more major crimes he halts is a scandal involving Sivana industries, which obviously introduces Dr. Sivana. Sivana is in his office when he receives word that his operation has halted by a caped man in red and the press are all over it. The media request a response from Sivana, he gives the company line.
-Just when things seemed to be going good, of course, Black Adam returns.
-Adam finds out about the altercation that Captain Marvel had with Sivana industries via a television in a bar (which he promptly destroys). Adam flies to Sivana's building and creates a gaping hole in the building to access Sivana's office. He grabs Sivana by the neck and asks him where he can find Cap. Sivana says he doesn't know, but the explosion was enough to get Cap to show up at the building.
-I think we all know where things go from here.
-Black Adam fights with Cap in some epic action sequences through Fawcett City. Adam lectures Cap on why those with power have more worth than the weak. All that jazz.
-It ends with Adam being beaten and banished once again.
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I did this on the fly so don't hate me for any errors or loose-ends. I know it still needs revision. :P
I don't feel like going into too much detail on the third act, because quite honestly, it is all about the action. Words can't describe how cool the fight could be on film.
While I think Dr. Sivana should be introduced, I do not think he should become very involved at least until a sequel where he can conspire against Captain Marvel in collaboration with another villain.