Five Nights at Freddy's: Book Six: The Possession of Mike Schmidt

In Five Nights at Freddy's: Book Six: The Possession of Mike Schmidt, Mike Schmidt, still haunted by the traumatic events of his past at Freddy Fazbear's Pizza, is offered a job as a night guard at the newly opened Circus Baby's Pizza World. Despite its modern and sleek appearance, the facility holds an unsettling atmosphere, with its advanced animatronics and strange occurrences. As Mike begins his night shifts, he encounters eerie behavior from the animatronics, including Circus Baby, and begins hearing a mysterious voice over the intercom. The voice, which seems to know everything about his past, gradually reveals itself as Ennard, a malevolent entity made from the animatronics, controlling them and attempting to manipulate Mike.
As the nights go on, Mike uncovers the dark history of Circus Baby's Pizza World, realizing that the animatronics are not just entertainment robots, but vessels for trapped souls, including the vengeful spirit of Elizabeth Afton, daughter of the infamous William Afton. Mike's investigation reveals that he is now tied to Afton's legacy, with Circus Baby and Ennard at the center of a twisted plan to continue the cycle of torment and possession. In the climactic final night, Mike is fully overtaken by Ennard, his body and mind consumed by the entity. The story ends with Mike's fate sealed, now part of Ennard's dark design, continuing the cycle of terror that has plagued him for so long.