Inside a dark, remote warehouse, seven members of an unnamed midwestern militia meet. They’ve all heard via radio or police scanners that an unnamed, armed shooter armed with a modified AR-15 has opened fire on a police funeral. The assailant also plant IEDs and the casualty rate is therefore very high. This means the authorities will be scouring the countryside, raiding all known militia groups and their affiliates in the region. The men’s concern quickly turns to panic when they discover that one of their AR-15 is missing from their weapons cache, along with body armour and explosives. Is one of their own the shooter? Ford (Chris Mulkey), the group’s no-nonsense leader, asks fellow member Gannon (James Badge Dale), a former police interrogator, to question all the men and determine who is responsible. However, matters prove more complicated as Gannon knows that one other member, Noah (Brian Geraghty), is an undercover cop. Can a solution be found before the police inevitably come calling?