In 1974, young Thaddeus Sivana is  in upstate New York during a snowstorm in her car with her abusive father and brother Sid. He is constantly taunted and verbally abused by them. He was suddenly transported to the Rock of Eternity, a mysterious temple  in another dimension. The ancient wizard Shazam searched for the pure of heart for centuries after the previous champion published The Seven Deadly Sins, bestowing his power and name as a champion. Thaddeus is tempted by sin and promises that if he releases sin, he will give him power. Finding Thaddeus unworthy, the wizard  magically returns him to the car. Sivana's frustration and confusion lead to a car accident, leaving her father  paralyzed from the waist down and resenting him even more. Both he and Sid blame Thaddeus. Sin sends Thaddeus a message via an 8-ball toy, telling him to find them. continues to run away from his foster home to find his mother. He locks some police officers in the store and uses her computer to try and find her mother, but is unsuccessful. He will be placed in a communal apartment run by Victor and Rosa Vazquez, along with five  foster children: Mary Bromfield, Pedro Peña, Eugene Choi, Darla Dudley and superhero enthusiast Freddie Freeman. An outraged Sivana succeeds in his lifelong quest to find a way back to the Rock of Eternity. When his eyes merge with his body, he becomes a vessel of sin and overwhelms the sorcerer. He soon used his newfound powers to kill his father, brother, and the board of directors of Sivana Industries. 
Billy protects Freddy from school bullies  and is chased by the subway  to the Rock of Eternity. The Wizard chooses Billy as the new champion. By saying the name "Shazam" Billy transforms into a grown-up superhero.The wizard apparently died leaving behind his wand. Freddie is drawn into Billy's trust and helps Billy explore his newfound powers, including superhuman strength, near-invulnerability, and electrical manipulation. Saying "Shazam" again will bring him back to his original body. Freddy posts a new superhero viral video, and Billy begins skipping school, trying to use his powers to get money and fame.  Billy and his brother are hailed as heroes. They return sin to  prison and realize they can use the Rock of Eternity as their superhero headquarters, and Billy finally accepts his foster parents and siblings as his "real" family. In his superhero form, he had lunch with his brother at school, revealing to Freddy's surprise that he had also invited Superman.