Following Wozniak's discovery that Stahl's target is his close friend and Mayoral Candidate, Julia Ayers, Wozniak launches an all-out war with Stahl. Meanwhile, Harlee dives into an investigation that takes an unexpected turn into her own past - and ultimately throws her in the cross-hairs of Wozniak and the FBI. At the precinct, a new, unwelcome presence threatens to uncover the crew's deepest secrets.

Realizing that Stahl will stop at nothing to arrest Julia Ayres, Harlee decides to investigate on her own and determine whether there's any truth in his allegations of Ayers' active business with the mob. Wozniak is confronted with a drug case that forces him to face the darkest demons from his past, his daughter's death, while exposing the origin of his loyalty to Ayres.