On the annual day of Sonja's death, her children are attacked and the hunt for the villains begins.

Emil suspects that the attack on the siblings may be linked to his witness. Gustav, Nina and Linus try to find out who is responsible and eventually they get a lead. But what they don't know is that someone else is one step ahead.

As the threat to the siblings grows, a guest from the past shows up at Gustav's house. Nina is forced to work with Barry's dodgy business associates to keep the firm afloat. But something goes wrong.

The only way to try to eliminate the threat seems to be to appease the perpetrator. Emil manages to get the identity of the perpetrator, but in the process of making the arrest, something else catches his attention.

The children are taken to safety and help comes from unexpected quarters. When the perpetrators show their true colors, everything's turned upside down. It's no longer a case of an external threat, it seems to come from within.