Synopsis for 04×08: Sherlock discovered Detective Bell coming out of Joan’s room and suspects they might be engaging in a relationship. Meanwhile, a woman turns up dead in her vehicle, 8 weeks pregnant, and just so happens to be the daughter of a serial killer.
Sherlock came home to the Brownstone just as Detective Bell made his way out of Joan’s room and down the stairs. He was immediately suspicious and inquired into Bell’s presence there, to which he did not receive an answer. Joan refused to give him any information about the reason behind Bell’s presence in their home, and Sherlock seemed quite flustered by it.
The NYPD responded to the scene of a murder where a young woman was left dead in her car. They had a recording of the incident leading up to it, but it didn’t tell them much. It seemed like she may have known her attacker because of her pause when she probably turned to see who it was and how she seemed to relax for a moment before she was brutally killed.
She also turned out to be eight weeks pregnant even though she had gotten her tubes tied, and her husband was physically unable to produce viable sperm that could get her pregnant. This led the detectives on a hunt for an affair (though the husband denied that being possible).
Joan went to the victim’s OBGYN and snooped around to try and get information on the pregnancy, like the name of the father. The OBGYN was pretty set on not telling her anything, as the focus was the mother and child not any of the drama surrounding it. But Joan distracted her, got her out of the room long enough for her to get into the victim’s medical file and get some information.
Later, Sherlock found out that Bell had been in his home because Joan had been helping him study for the Sargent’s exam. Sherlock didn’t understand why Bell hadn’t come to him, as he was an excellent teacher. Bell shrugged him off.
The team was able to confirm that the victim had been having an affair with whoever fathered the child, and that they had scheduled a meeting at Sing Sing. It turned out the meeting was to see her father who was a convicted serial killer (the Triborough Killer). He worried that his daughter’s death may have been due to his crimes.
Perhaps one of his victim’s family members had decided to take revenge by killing his children, who had received threats when they were young and had gone so far as to change their names and move away. He wanted them to make sure his son was alright and gave them what information he knew, but asked that they track him down.
They found the brother, who admitted he and his wife knew about the affair because they’d seen his sister with another man in public. However, they were sad to hear about the murder, and explained how they’d worked so hard to distant themselves from their father.
Sherlock pestered Bell about the exam again and tried to help teach him. Bell admitted that he didn’t want Sherlock helping him because Sherlock would notice too much. He said that he didn’t actually want to take the Sargent’s exam, but his mother had recently lost her job so he needed the bump in pay to try and help keep her steady while she figures out what’s next. The only way to do that would be to move up in the ranks, even though it isn’t one of his personal goals as he loves what they do. Sherlock immediately offered him a loan, but Bell turned him down because he wanted to get it all together on his own.
After a bit more detective work the team was able to figure out who the victim’s baby daddy was. It turned out she’d been working pretty closely with a relator who was wanting them to sell their house. She’d been having an affair with him (though he initially denied it, being a married man). He had been having an affair with her in an attempt to get close to her father, as his mother had been one of the father’s victims back when he was out on the streets.
He wanted to talk to her father, not get revenge. He just wanted a face to face and claimed that his relationship with the victim would allow him to do that. She understood, and that’s why they’d agreed to meet at Sing Sing before she was killed. He was finally going to get to talk to her father.
Once it was revealed he was the one she’d been having an affair with, he got jumped outside of one of the properties he was overseeing and had the crap beaten out of him. They turned to the victim’s husband, who had used scaffolding to beat the guy because he was upset about the affair. They tried to pin her murder on him, too, but there was no way he could have done it. He may have been angry at the relator and would admit to assaulting him, but he didn’t kill his wife. If it wasn’t the husband, and wasn’t the man she was having an affair with, then who on earth killed her? Sherlock had to go back to the audio recording to see if there was something he missed.
Finally, he got it. In the video she says “No!” followed by a softer “no” when she seemed to recognize her attacker. As she was attacked she continued shouting, but Sherlock began to think that she wasn’t just saying “no.” He’d found a picture of her and her brother from when they were young and on the back of it was written “No,” short for Noah, her brother’s given name (which had been changed to Craig). He believed that it was Noah who had killed her that night and she was saying his name. They brought him in for questioning based on that, and he admitted to everything.
Apparently both he and his sister had taken measures to make sure they could never reproduce. They promised each other they would never have children. Their father’s line would end with them, so there wasn’t any chance his evil would be passed onto a child. She’d gone back on her promise, though, when she got pregnant and decided to keep the baby. He refused to allow her to have a child that would carry on their father’s line, and because of the promise they’d made, killed her to prevent her from having a baby. He’d been upset that she’d broken the promise in the first place and went to extreme measures to stop her.
Joan and Sherlock gave Bell a case to work on as a final “test” for his Sargent’s exam. He was able to solve it, but as he was heading in for his exam, Sherlock tracked him down. He explained that thanks to Bell’s work on a case he believed to be fake, they’d been able to bring in a fugitive with a bounty on his head.
The bounty just so happened to be a big sum of money that Joan and Sherlock took a small portion of, but bestowed the remaining amount onto Bell since he was the reason they’d caught the guy. He earned the money to help his mother fair and square and accepted it, but still went in to take the exam anyway.