LAPD K-9 officer Jake Rosser (Aaron Eckhart) and his K-9 partner Ace battle it out on the streets of LA when they get into a shootout with local drug dealers and Ace is shot dead. In a moment of crisis, Jake tries to get an EMT to look at Ace and assaults him when he refuses, resulting in him taking leave from the force. Blocked by Internal Affairs, muzzled by his own superiors from finding the shooter's identity, Jake resolves to go rogue and partners with "Socks", a violent K-9 with titanium incisors and a mysterious past. Jake and Socks aim to uncover a vast conspiracy that has a chokehold on the city and take vengeance on those responsible.