The story begins with Harry Potter, now in his late 30s, working at the Ministry of Magic as an overworked employee. He is married to Ginny Weasley, and they have three children: James, Albus, and Lily. The focus shifts to their middle child, Albus Severus Potter, who struggles with the weight of his family legacy and the expectations placed upon him as the son of the famous Harry Potter.
Albus becomes best friends with Scorpius Malfoy, the son of Draco Malfoy, and they embark on a journey that sets the stage for the main conflict. They learn about a Time-Turner, a device capable of manipulating time, which has resurfaced. Albus, driven by his desire to prove himself, convinces Scorpius to help him change the past and prevent a tragic event from occurring.
Their time-traveling adventures lead them to various pivotal moments in Harry Potter's history, altering the course of events and creating an alternate reality where Voldemort reigns supreme. As they desperately try to correct their mistakes and restore the original timeline, they encounter familiar characters from the original series, such as Severus Snape, Albus Dumbledore, and Hermione Granger.