Mackey tries to help an old acquaintance find a wayward teenager, but the search quickly turns ugly when the missing teen appears to have been involved in a shoot-out. Meanwhile, Shane heads out into the field with his new partner Army, teaching him shady police tactics and seeing how far he'll go to be partnered up. Plus, Aceveda spends his last day trying to bury Vic for good, which makes things difficult for Rawling trying to take his place.