Mike is hired by Circus Baby's Entertainment and Rental, an underground facility storing animatronics from the closed Circus Baby's Pizza World. The facility's AI, HandUnit, greets Mike each night and assigns him maintenance tasks. On the first night, everything runs smoothly: using elevated control pads, Mike checks on and, if necessary, administers electric shocks to the three animatronics—Ballora, Funtime Foxy, and Circus Baby—to ensure they remain active, before leaving. On the second night, the power goes out, the animatronics come to life, and Circus Baby warns Mike of the danger posed by the other animatronics. She instructs him across Ballora Gallery and assists him in resetting the circuit breakers. On the third night, after performing maintenance work on Funtime Freddy, Mike is attacked by Funtime Foxy and is placed in a springlock suit by Circus Baby for his protection, from which he must escape while repelling Minireenas on the fourth night.
On the fifth night, Mike discovers two hanged technicians in the location where the animatronics should be, preventing HandUnit from detecting their absence. Circus Baby directs Mike to dismantle her empty shell in the Scooping Room, where the animatronics' endoskeletons are extracted, explaining that this is necessary to "save what is good so the rest can be destroyed." However, she warns him that he is being pursued by the animatronic Ballora, who intends to kill him. Between nights, Mike watches an animated sitcom at home. Elizabeth, William Afton's daughter begging him to play with Circus Baby, despite her father's insistence that she must stay away.
