John Corey is a fictional character created by author Nelson DeMille. He is a former NYPD homicide detective who becomes a private investigator. Known for his sharp wit and sarcastic humor, Corey often finds himself embroiled in complex criminal cases that require both intelligence and bravery. Corey first appears in the novel Plum Island, where he investigates the murder of a scientist. Throughout the series, he navigates various challenges, including personal struggles and dangerous situations, while showcasing his resourcefulness and determination to uncover the truth.