Constantineâ€™s ninth episode, â€œThe Saint of Last Resorts: Part 2,â€ starts where the midseason finale left off. We find John still dying in the sewer after Ann Marie shot him. In order to heal himself and escape the invunche, John casts a demon inside himself. Luckily, it works. Now, John and Chas must find a way to cast the demon back out before it fully possesses him.
Meanwhile, Zed wakes up in the back of a van after being sedated by the men that her father sent. The driver of the van tells her that her father will be happy that she is still having visions. Using her fear of ever going back to her father, Zed attacks the driver of the van and gives him the sedative that was meant for her. Once Zed is free of the driver, she gets in contact with Chas who asks her to come down to Mexico to help exorcise the demon from Constantine before the demon â€œtakes up permanent residenceâ€ in his body.
Unfortunately, it looks like the demon went for a joyride when John wakes up surrounded by dead bodies with a SWAT team putting him in handcuffs. Heâ€™s taken to a Mexican prison where a lawyer tries sitting down with him. John only asks that he pulls some strings to get him out of there as soon as possible. Now that they have no idea where John is, Chas and Zed convince Ann Marie to help find him using her powers. After finding him in the prison, Chas and Zed look for a way to get to John. Meanwhile, the lawyer who was speaking with Constantine is taken over by a snake-like demon who has unfinished business with John.
To get into the prison, Zed pretends to be a hooker, and Chas punches a guard to get locked up. As they are finding a way to help Constantine, Ann Marie joins them. She explains that even in prison, they still have respect for religion. After being assured that they would not be disturbed, Chas, Ann Marie, and Zed are ready to begin the exorcism. Only moments after they start, the demon lawyer enters the room. Constantine recognizes immediately that this is the serpent demon who tempted Adam and Eve. Realizing that there is only one way to kill this demon while keeping John alive, Ann Marie uses the knife meant for John (should the demon take over) on the serpent demon.
Now, they must find a way to get Constantine out of the prison. Chas works with the inmates to gather enough heroin â€œto kill a pack a dolphinsâ€ as Chas notes. By giving John the heroin, it essentially kills him, so Ann Marie and Chas can smuggle his body out of the prison. Barely escaping, they all head back to Johnâ€™s house to try the ritual again.
Back at the house, John explains that it must be Ann Marie who performs the ritual. Since the demon is so strong, she is the only one who has enough faith to be able to complete the ritual. Even though Ann Marie knows that should the demon come out he will say anything to throw them off, she is still caught by surprise when the demon tells her that she canâ€™t do it. Ann Marie almost backs down, thinking that she isnâ€™t strong enough and canâ€™t save John. Zed convinces her that she has to let go of her guilt at what happened at Newcastle and continue the ritual. Gathering the strength needed, Ann Marie finishes the ritual and sends the demon back to hell.
When all is said and done, Ann Marie leaves to go back to her convent in Mexico. Before she goes, she speaks with Zed about the men who are after her. Zed hasnâ€™t said anything to John, but Ann Marie tells her that she should really tell John what is going on. During the exorcism, the demon said some nasty things to Zed about eventually running back to her Daddy.