Lucifer and Chloe investigate a mysterious masked killer who is poisoning college students.

Lucifer must find the antidote to the Professor's poison before it kills Chloe. He travels to hell to find the Professor's soul and get him to turn over the antidote. While he's there, he is forced to confront his guilt about Uriel's death. Mom heads to hell to get Lucifer back, but Lucifer still feels betrayed by his parents because of something he discovers.