Sam asks to talk to Sock privately in his car outside the Work Bench. Sock gets in… and a zombie Mr. Oliver says hi. Sock manages to get himself under control and Mr. Oliver explains he can't entirely die thanks to his deal with the Devil. Sam admits he did it to Sock so that he could watch when Ben comes out and sees Mr. Oliver. Ben just wants to go home and take a bath, but Sock convinces him to hop in for a ride. Ben starts screaming.
Kristen is practicing karaoke and Sock is leering at his half-sister. Ben explains that he and Nina have their sex lives under control, but Sock insists nothing can contain his sexuality. At work, Sam is parking riding lawn mowers when the Devil decides to play bumper cars. The Devil then gives Sam the new vessel, a stake, and explains that his target is an escaped soul, Tracy Reed, who thought she was a vampire. The Devil knows Mr. Oliver is back but points out that he's the one who arranged for Sam's soul to be sold.
The guys go to Tracy's address and she attacks them, but Sam finally manages to stake her. The guys discover a baby rattle, a carriage, and a birthing book, and hear crying upstairs. They go upstairs and find a baby girl. The guys take her to the DMV and Gladys explains that some souls escape from Hell to give birth. She tells them they can look after the baby, or she can send it back to Hell. The guys decide to keep the baby and Gladys suggests Sam turn to Andi for advice.
Ted brings Andi an envelope for her: it's an invitation to dinner, apparently from Sam. Ted is more interested in pointing out how Andi is screwing up now that she has his job, until she orders him out.
At home, the guys aren't sure what to do, and Ben figures they need mother's milk. Kristen comes in and cradles the baby, and Sock admits he's jealous of the baby. Ben pulls him off to the side and says that Sock needs help. Ben suggests he play racquetball to release his tension, but Sock isn't big on exercise. That leaves chemical castration, and Sock would rather do that then exercise.
The guys are taking care of the baby when Tony pays a visit to warn Sam that demon assassins are after him. Tony admires the baby and admits he and Steve had planned to adopt. They offer to let Tony take the baby off of their hands, and Tony thinks it's fate. Tony names her "Stevie" after his dead life-partner.
Andi arrives at the restaurant to find the entire place empty except for her date: Morgan. She's disgusted with him for ambushing her and insists he's with Sam. Andi says she'd never date him even if she wasn't with Sam, because Morgan is the son of the Devil. Morgan points she's okay with Sam, and Andi is shocked to hear the news.
Kristen is still practicing karaoke and Sock takes one more look at her before he goes to the doctor. They hear a tapping sound and discover that Mr. Oliver is in the backyard setting up a badminton net. Sam says he has work and Mr. Oliver admits he has a lot of free time. Sam suggests he call ahead. At the Work Bench, Andi asks if Sam has anything else important to tell her. When he doesn't say anything, she tells him she knows he's the son of the Devil. She hauls him into the office and Sam admits he figured she'd be upset. Andi fires him but he points she can't legally do it. Instead she hits him, puts him on dumpster duty, and tells him to clean up the coffee she just spilled.
Sam starts cleaning, but then runs after her. He ends up in the Devil's office, and the Devil tells him that he needs the baby back. Sam doesn't want to send a baby back, but the Devil says it's a bad seed destined for evil. Sam has 24 hours to use the vessel to stake it, or the Devil will do it himself.
Sock is psyching himself up to take the pills when Sam tells them they're heading over to Tony's for lunch and a chance at the baby. Mr. Oliver tries to scare them and then realizes that Sam is blowing him off and shirking his family responsibilities. Mrs. Oliver blames Sam's dad for his turning into a zombie, and Sam has to agree. Sam finally says Mr. Oliver isn't his real father. Mr. Oliver explains he can't say anything due to his deal, but he loves him. Sam says now he has to send a baby to Hell thanks to his father.
The guys enjoy Tony's lunch and complain that it needs mushrooms and fresh tomatoes. Tony goes to the grocery store and agrees to let them watch Stevie. Sam tries to stake Stevie but he can't bring himself to do it. He suggests they sing it to sleep so it's not looking at him when he kills it. Just as he prepares to stake Stevie, Tony comes back early. He goes berserk and attacks them., and says the Devil lied and the baby isn't a monster. Tony promises to raise the baby to be good but Sam warns the Devil won't stop coming. Ben suggests they baptize Stevie and washes away its original sin so the Devil won't have any claim on her. Tony agrees to the baptism.
Ben sets up an emergency baptism with Father Ortega. Tony's asked Andi to stand in as the mother. As the guys go inside, Tony introduces Andi to the baby and says that Sam will be standing in as the father. Tony can't enter consecrate ground but he figures Sam is half-human and should be okay. He picks up that Andi has issues with Sam, and explains that Steve appeared to him and convinced him that Sam was worth saving.
As Sam and Andi take Stevie in, Sam doesn't burst into flames. Andi admits she isn't sure about him but Sam believes there's good inside of him. As they sign the baptism certificate, the carriage wheels itself out of the church on its own. Sam manages to get out just as the doors close on their own. The carriage rolls itself across the street through traffic, into an empty storefront office, and into the backroom. A pit has opened up to Hell and the Devil is waiting.
Sam manages to grab the carriage but the Devil takes Stevie. He figures Sam sees Stevie as an innocent victim screwed by someone else's bad choices, but is sure that it's the baby's nature to be evil. Sam argues that the Devil should let her stay to wreak havoc on Earth and give the Devil more souls. The Devil agrees and hands over Stevie, and then laughs. He's sure Stevie and Sam will both turn out, but he'll let Sam find out and enjoy the expression on his face when Sam realizes the truth.
Sock prepares to take his pills but spits them out when Kristen startles him. He vaguely explains that he needs to tame his spirit to be a better brother. Kristen throws the pills away and insists she doesn't want him to change. She asks what she can do to help and Sam goes with Plan B: lots of racquetball and screaming.
Morgan stops by to talk to Andi, but she warns that she's wise to his tricks. She insists that Sam will always be good. Morgan congratulates her, but warns that evil is sometimes hard to see, particularly when it comes in a friendly form and love is involved. He takes off, and Andi worries.
Mr. Oliver shows Sam his new place: a storage facility. Sam admits he can't stay mad at him and he's a good person because of how Mr. Oliver raised him. He has an idea, and later the guys put Mr. Oliver in a freezer and move him into Sock's garage.