Harlee struggles with becoming an FBI informant while Wozniak suspects every member of his crew. Paranoid that Wozniak's search will lead to her, Harlee suggests polygraphng the entire crew, a plan that backfires. An appeals case sends Wozniak to watch tapes from his first encounter with Harlee, revealing a dark secret from their past. Meanwhile, Espada helps Tess deal with her husband's infidelity.

After Saperstein's death, Harlee realizes there are no lines Wozniak won't cross and decides to help Stahl's investigation. The crew retaliates against a pair of abusive cops after they harass Harlee's daughter Cristina and her boyfriend. Wozniak makes Loman feel like a part of the unit.