At some point, Carlisle became a professor at Malibu State. One day, an Uber car he was riding in crashed and caught fire. He managed to escape, but instead of helping the student who was driving, he saved his laptop, which contained his dissertation. The car exploded, killing the driver. Carlisle became a publicly hated figure after this event, losing his job and his family. He later became a professor at Pasadena University, however he secretly formed a plan to prove that he couldn't be blamed for what happened. He hired a criminal named Burt to smuggle specialized poisons into the country. However, the package was stolen by Andy Kleinberg, thinking they were drugs.
Carlisle tracks Kleinberg to an airport in Chicago. Kleinberg accidentally poisoned himself, and asks what is happening to him. Carlisle simply strangles him, and takes the package back.
Carlisle sets his plan into motion. First, he poisons a student named Rick Cormier via flu shot. Then, he hacks the e-mail of a student named Matthew Hoffing and sends an email to Johnny Kane, a famous actor. He tells Kane that Cormier will die unless he cuts up his own face. Kane doesn't comply, so Cormier dies the next day. His death causes Chloe Decker and Lucifer Morningstar to investigate. Carlisle then poisons another student, Ashley Corbett, and sends an e-mail to Dr. Gwendolyn Scott, a renowned surgeon. He tells her that if she doesn't destroy her hand, Corbett will die. Lucifer and Chloe see the e-mail, and go to find Corbett. She is found and hospitalized, but the doctors are unable to treat her poisoning. Left with no other choice, Dr. Scott mutilates her hand. Carlisle is sent a picture of her hand, so he sends Dr. Scott a bag containing Corbett's antidote. Corbett receives this in time and survives. Carlisle believes that the doctor only chose to save Corbett because she was being observed, so he abducts Leon Klem, a track star who's leg he attaches to a guillotine, and a student named Benjamin Tibi, who he attaches to a poisoned IV. The LAPD learn about the flu shots and by extension, Carlisle's identity. Chloe then sends him an email, challenging and insulting him. Carlisle then video chats with them, informing them of the abductions. Chloe figures out that he is at Pasadena, so she and Lucifer go there to arrest him. Carlisle hides from them behind bullet-proof glass, and then offers a choice to Chloe. Enter the room with the abductees and she gets the antidote, but she will die due to poisonous gas. He then flees, and Chloe chases after him. During a brief struggle, Carlisle injects her with poison. He is eventually cornered by Chloe. She says he can still do the right thing and save Tibi, but Carlisle says choice is an illusion and cuts his own throat. Lucifer saves both Tibi and Klem, remaining unharmed himself due to his immortality. Due to his crimes, Carlisle's soul goes straight to Hell, where he relives the car crash over and over.
A Good Day to Die
Chloe begins dying due to Carlisle's poisoning. Lucifer manages to get the ingredients for the antidote, but not the formula, which Carlisle never wrote down or told to anyone else. In order to save Chloe, Lucifer stops his own heart and goes to hell. He makes his way to Carlisle's cell. Carlisle asks him how he can escape, and Lucifer says that the only way to get out is to believe you no longer deserve it. He then says that making amends for his past misdeeds may help end his guilt. Carlisle gives Lucifer the formula, and asks if it makes things right. Lucifer says, "You tell me" and starts walking away. Carlisle doesn't stop feeling guilt, so his torture resumes. Before he leaves, Lucifer looks back and reveals himself to Carlisle as the real devil. Lucifer is later resuscitated, and he uses the formula to save Chloe.
- Andy Kleinberg- Strangled for stealing the poisons.
- Rick Cormier- Posioned via flu shot and died the next day.
- Ashley Corbett- Attempted; poisoned like previous victim, but was given the antidote when Dr. Scott complied.
- Benjamin Tibi- Attempted; abducted and attached to a poisoned IV, but was given the antidote by Lucifer.
- Leon Klem- Abducted and attempted to make amputate his own leg.
- Chloe Decker- Attempted; poisoned via injection, but was later given the antidote.