Regan MacNeil is now seventeen, and although she appears to be normal after her demonic possession as a child, she is monitored regularly at a psychiatric institution. A troubled priest, Father Lamont, visits her there to learn about the death of Father Merrin when he was performing the exorcism on her four years before. Regan has no conscious memories of that time, but as the priest's investigation continues, the demon is brought back.

Regan MacNeil is now seventeen, and although she appears to be normal after her demonic possession as a child, she is monitored regularly at a psychiatric institution. A troubled priest, Father Lamont, visits her there to learn about the death of Father Merrin when he was performing the exorcism on her four years before. Regan has no conscious memories of that time, but as the priest's investigation continues, the demon is brought back.