In Nefárious, serial killer Edward Brady (Sean Patrick Flanery) – sentenced to death for the murders – reaches the day of his execution. However, first, he must undergo a final consultation with a psychiatrist to certify that he was aware of his crimes while he was committing them. But when his old doctor takes his own life, Edward is evaluated by a new doctor, James Martin (Jordan Belfi). Martin believes he will deal with just another common assessment, but is surprised when Brady claims to be, in fact, a demon disguised in the man’s body. Now, the doctor must discover the truth behind the case.