In a psychiatric hospital in Washington D.C., the tenacious homicide detective, Lieutenant Kinderman, faces a series of mysterious murders that bear unsettling similarities to a case from years past. The shadow of the infamous "Twin" haunts Kinderman once again, as he grapples with the horror of his past, when he encountered a life-changing exorcism. As the bodies begin to pile up and the killer’s methods grow increasingly twisted, Kinderman is forced to confront his own inner demons.
In the search for answers, he meets Father Karras, a priest and psychiatrist who was present at the legendary possession case. However, Karras appears to have died long ago, adding a complex dilemma to the already distressing situation. As the line between madness and reality blurs, Kinderman discovers that the crimes are not merely the work of a murderer, but the result of supernatural forces threatening to consume his life.
With nods to the original story and a blend of psychological horror and mystery, the plot escalates towards a dark climax that will compel Kinderman to confront evil in its purest form. This terrifying odyssey becomes a struggle not only to solve the case but also to safeguard his own soul against the impending threat of the unknown.