In the film “Mommy,” Patty McCormack portrays a mother with an unhealthy fixation on her 12-year-old daughter, Jessica Ann. Her obsession reaches a dangerous level when she discovers that Jessica Ann has once again missed out on the “Student of the Year” accolade. In a twisted attempt to rectify this, she murders the teacher responsible for not recommending her daughter. She trivializes the act as merely “a minor accident,” but the detective investigating the murder quickly becomes suspicious of her. Meanwhile, an insurance investigator, also doubting her innocence, attempts to get close to Jessica Ann to uncover the truth.