A man runs from pursuers in a car. But he's run over, then shot twice, outside a factory in Red Hook. Maggie notices a hand stamp, IR, on the victim. Scola and Tiffany locate the bar it came from. Surveillance shows the victim paying with a credit card, which helps identify him as Cole Dixon. His wife thought Dixon was an Uber driver. She mentions he has a safe in the garage, which has cash, a couple of burner phones, and a ledger in it. Maggie answers a text on one and sets up a meet. Maggie discovers that it's her FBI mentor, Gwen Carter, on the other end of that text. Gwen explained that Dixon is a professional informant. He told her that he was onto something that could cost thousands of lives. A man that Dixon was seen arguing with says that Dixon had met with chemist Walt Taylor. Taylor is found shot just like Dixon but he had built a bomb, which is missing. A witness says two Asian men had run out of Taylor's house carrying a big duffel bag. A crypto payment to Taylor was made by Rex Yu, a member of the East-19 Chinese gang. Yu gets away from the team when Gwen pulls up for the second time in as many days. Using the GPS in Yu's recovered vehicle, Gwen determines his target, anti-Community China business Victor Ho, who lives in the penthouse. Maggie discovers a med-pen in Gwen's bag. OA locates Yu on the roof of a nearby building, hoping to catch Ho in the blast zone. Yu runs and OA has to be talked through disarming the bomb. Yu overcomes Maggie when they battle in a garage but Gwen shoots him. Maggie convinces Gwen to report her MS.