Harper and Chen run a community policing meeting in which Harper puts Chen in charge and isn’t happy when she promises to looking into issues. It leads them to find vagrants smoking meth in a sewer drain. Two men attack them. Harper takes down hers easily but she has to save Chen.
Chen is upset when Harper tells her she may only be cut out for community meetings. When Chen pushes back, Harper tells her that she has to learn to fight like a 5’6” woman against men much bigger than her and most men don’t know to teach her that.
Later, Harper suspects a man is making bombs and wants to take his trash to get a DNA sample to see if he matches an old case. Chen distracts him but when the man sees Harper, he arms the bomb under his floor that will be set up if Chen steps on the pressure plates.
Chen uses the wear marks on the floor to get passed the pressure plates and arrest the man before he sets off another bomb. Harper admits she was wrong about Chen and agrees to give her advice when she asks for it.
West and Bradford attend a community football game where they meet 14-year-old AJ but are concerned when his mother shows up and tells him he has to quit the team and they are leaving town now. When Jackson and Tim try to follow up, someone throws a molotov cocktail into the woman’s car but she still won’t tell them what is happening.
AJ comes to Bradford to say his mother is missing. Her ex-boyfriend wanted her to be a get-away driver for a heist and when she refused, he threatened to kill AJ. AJ only knows that the heist was taking place this afternoon down town but doesn’t know exactly where.
On her off time, Lopez takes a one day security job guarding Mingus Kemp, a high end jewelry broker who is in LA to buy $2 million in diamonds. Turns out that AJ’s mother is being used to help rob the diamonds. Angela calls in backup and she, West and Bradford take down the crew and save AJ’s mother and the diamonds.
Jessica tells Nolan she might be pregnant. When she realizes she’s not pregnant, she’s disappointed. She’s decided she wants to be a mom, but Nolan doesn’t want to be a father again right when he’s starting a new career. He says that maybe he’ll feel differently in a year or two, but Jessica realizes she doesn’t have the time to waste. She fears she’ll end up hating Nolan and breaks up with him.