Frank Wagner goes deeper undercover to infiltrate Europe's most dangerous Mafia, the Russian-est, consisting of ex - KGB officers.

John Falk is on a routine mission with the Gothenburg police special unit GSI. With the help of a Norwegian undercover police and a civilian infiltrator in one of Gothenburg's heaviest criminal gangs, the GSI are trying buy six assault rifles and thus get them off the street. But suddenly everything changes when a new unknown player suddenly and immediately wants to buy not only those weapons but even more, including armor-piercing shells. GSI realizes that this can not be any ordinary robbers. Someone will start a war on the streets of Gothenburg. At the same time as the situation gets more and more complicated for John Falk's infiltrator Frank Wagner when the leader of the gang he infiltrated realize that one of his own leaking to the police.

Johan works in tandem with the GSI organized crime unit to bring in a cadre of armored car robbers

A car explodes in front of a primary school where GSI boss Patrick Agrell has just left his children. The event reunites Johan Falk with Leo Gaut, a former criminal restaurant owner who Johan put behind bars a decade ago.

Five men break into Frank Wagner's apartment. Frank is able to escape and seeks out the help of Johan Falk. Has someone leaked that Frank is working with the police? Frank and John don't know who knows what and whom to trust.

It's been two years since John Falk and Frank Wagner broke their cooperation and Frank started working undercover with the police. Frank's search for Kevin crosses Johan's investigation and opens up a new collaboration between them - with the big difference that this time it's personal for Frank.

GSI second in command, Sophie Nordh, flips gangster leader Seth Rydell and convinces him to infiltrate a rogue military group. For the first time GSI Chief Patrick Agrell realizes that he is using a ruthless psychopath as an infiltrator. Can Seth be trusted or does he have his own agenda?

It's a beautiful day in Slottsskogen, Gothenburg idyllic city park, when suddenly the unthinkable happens - gunfire amidst all people. Two gangsters shooting game against each other and a large police operation starts. The conflict grows rapidly to involve several gangs from Gothenburg underworld. GSI switched to try to identify a new thread which proves to be both larger and better armed than any other. The only clue is a tattoo on one of the killed gang members.

A group of young robbers, specializing in robbing shopping center security guards, are raging through out Gothenburg. A robbery goes awry when an innocent passerby is killed. Ricky, the gang's young leader, tries to quickly find an expert who can clean the money of the dye pack that exploded while Johan Falk, and his colleagues at GSI, accelerate their hunt.