Warning: Contains Spoilers
Killer: Rand Hardy, a high school teacher
Victim: Nancy Bailin, an intrepid high school reporter
Background: Nancy Bailin is fresh off busting one teacher for selling grades when she sees her newspaper advisor Mr. Hardy having an affair with her guidance counselor, Mackenzie Usher. She gets pictures of them kissing. Nancy wrestles with telling his wife, Carrie, who has just learned she’s pregnant.
Then, according to detectives, Nancy comes home one day to find her half-brother, Josh, robbing her house while high and he pushes her down the stairs, killing her. He is convicted and sentenced to 15 years in prison.
The Investigation: Angie is on the sidewalk outside the station on her way to catch a flight to Jamaica when Susan Bailin stops her on the street. She doesn’t believe her son killed her daughter and wants him released– and she has a bomb strapped to her chest.
Back inside the station, Susan holds the detectives and several civilians hostage as an Emergency Response Team led by Sgt. Fred Blunt assembles outside.
Angie suggests that if Susan really believes her son is innocent, she should release Detectives Paula Mazur and Brian Lucas to look into his case. Outside, Staff Sgt. Oscar Vega goes to the prison to talk to Josh. Josh confessed, but only after his step-father, Nancy’s father, browbeat him into taking responsibility. In reality, Josh was so high he has no memory of the murder. The confession means the murder was never really investigated.
Susan Bailin is an ordinance specialist with the Navy who tours the Middle East and literally wrote a book on IEDs -- the same one the bomb squad keeps in their vehicle. She is not messing around.
Lucas and Mazur head to Susan’s house to look at Nancy’s things. Mazur feels guilty that Angie put herself in harm’s way to get her out -- Mazur reveals that she’s pregnant.
Meanwhile, Rand tells his mistress Mackenzie that met with attorneys to sign the divorce papers, but his wife didn’t show. When Mackenzie asks to see the papers, he changes the subject.
In the autopsy files, Dr. Betty Rogers sees that Nancy had the pattern of a floor mat in her back -- but there was no floor mat in the crime scene photos at her house. It means she was killed somewhere else and Josh is one step closer to freedom.
To get at Nancy’s belongings in evidence, Susan agrees to trade the rest of the hostages except for Angie, who is taking being held hostage with typical Angie aplomb. They find the photos Nancy took of Mr. Hardy and Ms. Usher.
Vega calls Angie and gives her a coded message. Angie realizes a sniper is about to try to take out Susan through the windows and she hustles her to another room out of the line of fire. Susan picks up on the code and knows her time is running out.
Outside, the detectives think Blunt is a fool for even trying the risky operation.
Lucas goes to Rand’s house and finds Mackenzie there. He shows them Nancy’s pictures from seven months ago. Mackenzie remembers that the day Nancy died, Rand signed out early because his basement flooded -- but he tries to correct her that the flood was the day before.
Lucas doesn’t buy it.
Inside the station, Angie suggests they check Nancy’s bus pass to see where she went before she was killed. Angie learns that Nancy’s last recorded stop was three blocks from where Rand Hardy lives. She calls Vega and they compare notes -- no one has seen Rand’s wife Carrie for six months. She supposedly moved. Units head to Rand’s house.
Angie asks Susan to surrender, pointing out that if she detonates the bomb, she’ll destroy the bus pass and the only physical evidence that exonerates Josh. Susan finally relents.
Angie escorts Susan out, minus the bomb, and gets a big hug from Vega.
Back at Rand’s house, Mackenzie is starting to realize she might be dating a killer. She brings up the timing of the flood again and Rand tries to shut her down. When Mackenzie tries to leave for her house, he gets angry, but Lucas and other police are waiting outside the door to arrest him.
The Motive: Seven months ago, Nancy put the photos of Rand and Mackenzie through the mail slot at his house, then thought better of it. She found a spare key and let herself in to retrieve them, but when she saw furniture overturned inside and blood on the walls she looked around. She found Carrie Hardy dead in the basement and ran up the stairs -- right into Rand Hardy, who pushed her back down, killing her.
Rand admits to Angie that his wife is in concrete in his basement.
After being reminded about the bonds of motherhood, Angie uses missing her flight as an opportunity to have dinner with her son, Manny.