David Jacobs (guest star Noam Jenkins of Rookie Blue fame) is running for mayor. His motto is "I've Got Your Back." His wife, Grace, doesn't care for the campaign slogan. She also doesn't know that her husband is a killer. David murdered Tiffany Greenwood, the pretty 17-year-old girl who would always babysit his child. The question is... Why?
Angie is disturbed to see Tiffany's bloody body in the middle of the street. The victim was killed in a hit-and-run by a driver that was going at a high rate of speed in a custom car. Angie believes someone stole Tiffany's bag. David Jacobs is carrying a bag while anxiously leaving a parking structure on foot. He later shows up at the police station a bit more composed to support Tiffany's parents. He tells Angie that he's close with the family and had called Tiffany about a babysitting gig earlier. David is a former prosecutor who says he wants this young girl's killer caught.
We jump back in time to a day when Tiffany is babysitting for the Jacobs family. She invites her boyfriend, Kevin, over where they have sex on the sofa. Tiffany then breaks up with the guy. She's horrified to learn that the house has a nanny-cam. When her calls to Kevin go to voicemail, Tiffany hacks into David's laptop to find the video. She's horrified when she sees something she wasn't expecting. Tiffany swipes the laptop which David notices is missing after she leaves.
In the present day, Dr. Betty Rogers is surprised the windshield didn't break during the hit-and-run. This has Angie to believing the car may have been a racing car with unbreakable glass. This leads her to Tiffany's ex-boyfriend, Kevin. The guy is surprised to learn that Tiffany is dead. David is upset when Angie doubts Kevin is the killer because he doesn't have a motive. Nevertheless, Kevin is arrested. Angie checks out his car. She says the killer could have used a set of lock-pick keys called "jigglers" to steal it. Oscar is starting to buy into his partner's theory when they see that the car seat was adjusted for someone a lot shorter than Kevin.
Cell phone tracking records indicate that Kevin was likely at home during the time of the murder. Boyd gives the order to cut their prime suspect loose. When Kevin arrives home, he finds a package from Tiffany in the mail. It's a flash drive containing a video where David's panicky voice can be heard. In other news, Angie continues to search for Tiffany's missing bag. She also wants to know why David lied about calling Tiffany about a supposed babysitting gig. She's taking a lot of heat for her investigation. Prosecutor Donna Rivers asks to see all of her old case files.
Angie and Oscar stakeout Tiffany's funeral mass. They catch sight of Kevin confronting David about what he saw on the flash drive. The mayoral candidate scares the kid into turning over the file. Angie believes she needs to scare Kevin in order to get David to confess. Her plan works. David believes that Kevin is going to implicate him in exchange for immunity when he sees Rivers enter the box. Angie knows that the former prosecutor knows all about jigglers. He used a set to steal Kevin's car to frame him for the hit-and-run. David stole Tiffany's bag after he killed her. Angie still wants to know why?
David videotaped a sexual encounter with a prostitute. He made her don a blonde wig so she would look like Tiffany. The sex tape isn't enough to get a murder conviction, but the video Tiffany took of him trying to explain himself to her is. He claims that he's not a monster. That'll be up to a jury to decide. David is arrested for the murder of Tiffany Greenwood. Case closed.