Shazam’s origins go back to the 1940s, before Detective Comics, a.k.a. DC, even existed. (To make things really confusing: In his early days, he went by Captain Marvel, but was never that Captain Marvel.) Now, Shazam's name recognition is probably misplaced -- no, his superpower isn't being able to immediately identify songs you can't remember the names of. Instead, he's the alter ego of foster kid Billy Batson (Asher Angel), a sullen teen perpetually on the hunt for the mother he lost at a carnival when he was little. In the on-screen telling, after messing with the police to get his mom's potential address, Billy is transferred to a new home run by Rosa and Victor Vasquez (Marta Milans and Cooper Andrews), who provide loving parenting for a motley group of kids. There's video game-obsessed Eugene (Ian Chen), talkative and adorable Darla (Faithe Herman), ambitious student Mary (Grace Fulton), and quiet Pedro (Jovan Armand), who wants to get swole.
Billy's roommate is Freddy Freeman (IT's Jack Dylan Grazer), a disabled superhero aficionado, who gets bullied, and an incident with a few high school jackasses finds Billy reluctantly sticking up for his foster brother. On the way home, he's transported to a fading wizard's lair who transfers his power to Billy. All he needs to do is say "Shazam" and he's transformed into a 30-something man in a red spandex suit with old-fashioned matinee idol looks, a.k.a. Zachary Levi. Unbeknownst to Billy, the Wizard (Djimon Hounsou) needs a vessel for his mythical strengths because of an emerging threat: Thaddeus Sivana (Mark Strong) has harnessed the power of the Seven Deadly Sins, personified as gargoyle-like monsters, after being rejected by the Honsou's magical shaman for not being pure of heart enough as a child, and wants to wield the powers of Shazam to rule the world.
This is all to say that Sandberg and screenwriter Henry Gayden have a lot of set up to do in the movie's first act, which offers origin stories for both Billy and Sivana, all while introducing the audience to the Wizard's lore. (Fun fact! Shazam is actually an acronym for Solomon, the biblical king, and Hercules, Atlas, Zeus, Achilles, and Mercury, all mythological figures.) This expository section is the only place where the movie drags.