Merrin, an elderly priest and paleontologist on an archeological dig in Iraq, finds images of the demon Pazuzu and subsequently experiences other unusual phenomena. He had previously faced the demon many years ago during an exorcism in Africa. The find sparks a premonition that he will battle the demon again in a distant land. Merrin does not appear again until much later in the novel, when he joins the protagonist, Father Damien Karras, in Washington, D.C. to exorcise the demon from the body of a young girl. Merrin, who has a heart condition for which he takes nitroglycerin, dies during the ritual, leaving the inexperienced Karras to complete the exorcism himself.