Semir's older brother Kemal is coming back home. Unexpectedly, his friend Sky is attacked and a woman falls into a coma. During the investigation, Semir and Paul discover an environmental fraud scheme.
A day before his 50th birthday, after being haunted by his father's death for so long, a depressed Semir Gerkhan goes to discover what brought about his parent's sudden fate. Meanwhile, an old friend comes back to Cologne.
After a collective effort fails to defuse a truck bomb, a corrupt group of SEK officers, some of whom Semir knows personally, seeks revenge on police president Julia Dernhoff, blaming her for the botched operation and a dead rookie cop.
After Dana saves her friend Hannah from a kidnapping, she offers the latter a place to stay, for her safety and to protect her from a certain "Zoe." It later becomes apparent that the mysterious girl is closer than the officer may realize.
As the main suspect in his new girlfriend's murder, Paul tries to clear his name, enlisting whatever help he can get from his colleagues, and especially Semir. Meanwhile, Klaus Renner's dementia becomes prevalent.
A medic attending a crash site is motivated to kill two street racers responsible for killing an unsuspecting highway motorist; Semir and Paul must act quick in order to stop his rampage.
Susanne is brought to an impasse between her ex-boyfriend, Tommy Gerhardt, and her son's babysitter, Jana Burbach. The police secretary must do whatever it takes to protect her son when the latter party's gambling ties are again realized.
An OID investigation brings tensions between Semir and Krüger. The murder of police president Dernhoff throws the chain of command into turmoil as Cobra 11 holds off an extremist motorcycle club president from exacting further retribution.
Jenny is assigned as protective detail for a model; Paul and Semir embark to identify her stalker, whose ties to her are closer than they realize. With Klaus' worsening dementia, Paul also prepares to make a life-changing decision.
A hostage situation escalates at the Grand Hotel Bergmann, and previous tensions between Semir and Krüger come to a head. As Paul prepares to leave for New Zealand, a vengeful hotel manager seeks to avenge his son's eventual death.
