During a routine sting operation, Johan Falk (Jakob Eklund) and his colleagues at Gothenburg's GSI unit, stumble upon a lead to an unknown criminal element that is in the market for a number of military-style weapons, including armour piercing grenade launchers. GSI quickly realizes that these weapons aren’t intended for your average Gothenburg criminal intending to rob a convenience store. While all this is going down, Johan Falk’s underworld informant Frank Wagner (Joel Kinnaman) runs into some trouble of his own when the leader of his gang becomes convinced that someone is leaking information to the police.