Abby and Lina investigate the apparent suicide of a police officer and sexual-abuse allegations against the department chaplain. Meanwhile, Mackie and Abby's brothers plan a surprise birthday party for Abby and argue over whether to invite Danny or Brody.
Abby and Lina investigate an officer who is accused of stalking his female police psychiatrist. Meanwhile, Richie is partnered with an old family friend who plays fast and loose with the law; and Abby's relationship with Danny heats up.
An ex-con accuses some police officers of harassment. Meanwhile, Abby is propositioned by the detective investigating Richie's shooting of a teen, and Sheila visits the mother of the boy Richie shot in an attempt to cope with her own grief.
Chicago Internal Affairs detective Abby Kowalski (Rachael Carpani) investigates crimes in the department. In the opener, Abby, a beat cop, accepts a promotion to detective in Internal Affairs, which doesn't sit well with her family of cops.