Officer John Nolan (Nathan Fillion) and Officer Celina Juarez (Lisseth Chavez) go undercover for a public safety initiative but find themselves entangled in a perilous hostage situation aboard a city bus. As the crisis unfolds, Detectives Angela Lopez (Alyssa Diaz) and Nyla Harper (Mekia Cox) race against time to identify and apprehend the suspects behind the attack.