The father, John, is a devout Catholic who has always believed in the power of exorcism but has never witnessed it firsthand. That all changes when his daughter, Sarah, begins exhibiting bizarre behavior and speaking in tongues. After consulting with his local priest and discovering that Sarah is possessed, John hires three renowned exorcists – Father Robert, Sister Mary, and Reverend Jackson – to help rid his daughter of the demon.
As the exorcists begin their ritual, they quickly realize that this demon is unlike any they have encountered before. Its power is immense, and it is determined to not only possess Sarah but also use her as a vessel to unleash an even greater evil on the world.
As the exorcism drags on, tensions rise between the three exorcists as they each have different ideas on how to defeat the demon. Father Robert believes that prayer and faith are enough, while Sister Mary wants to use her knowledge of ancient texts to identify the demon's weaknesses. Reverend Jackson believes that brute force is the only way to defeat such a powerful demon.
As they continue their battle, the demon begins to taunt and torment each of the exorcists, revealing their darkest secrets and fears. With time running out and the demon becoming stronger with each passing moment, the three must put aside their differences and work together to save Sarah and prevent the unleashing of hell on earth.
In the end, it is revealed that the demon was summoned by a group of cultists who want to bring about the end of days. The exorcists are able to stop the cultists and defeat the demon, but not before Sarah is left with permanent physical and emotional scars. The exorcists must also come to terms with the toll that their battle has taken on them and their respective faiths.