In Dresden following a civil war in the ex-Soviet Union in the year 2000, Fischer is recalled from suspension to investigate the apparently racially motivated murder of a Danish nurse. Near her body, the words 'We are crossing' have been written, referring to the hundreds of thousands of refugees crowding the border with Europe. In the nurse's apartment, Fischer and his partner, Dix, find a porn disc and a cache of postcards, written by refugees but never sent. Following a roundup, Fischer meets Anna, a refugee selling porn, who may also be an informer. Dix goes to the Becks committee to provide details of his original birth, as he is half Turkish. Fischer asks Anna to find out where the nurse's porn disc was to be delivered.

Anna gives Fischer an address over the border. Together with Byrd, a member of Eupol, the organisation that polices the refugees, he goes to the house, but a woman flees. Byrd gives Fischer a one-week pass to avoid the border car scanner. Fischer returns to the house and, together with Anna, finds a boy hidden behind a wall. Fischer goes home and discovers that the woman has hidden in the trunk of his car. The penalties for transporting people outside of the quarantine zone are severe, so after letting her use the bathroom he gives her food and money and drops her off.

A girl who knew the nurse says that she referred to 'Star'. Anna crosses the border on a three-hour pass to tell Fischer that she can identify the Russian who collected the porn discs at the house. Fischer makes her identify him on their computer system, which is malfunctioning following a racist attack on their network. They find his address, but discover that Eupol is already there. Anna returns late and will not be allowed back in to Germany for months now.

When the refugee woman returns to Fischer's house, he asks Dix to serve as interpreter. The postcards were part of a smuggling operation into Germany. They take her back over the border to find her son, hiding her in the boot of their car. Byrd stops them at the border to show them the latest group of refugees to be arrested. When they return to the car, the woman has gone. The next day, Byrd calls to say he has found her body. He tells Fischer that Eupol has made deals with the mafia to stem the tide of refugees and warns him to be careful.

The woman's prints have been found in his house and Fischer becomes convinced he is being framed. Dix learns that his father lied about his birth certificate and that his citizenship is being revoked as a result. He tells Fischer to find the boy before the Russian mafia does. Fischer finds Anna and tells her the woman is dead. She was Anna's sister. They hide in the refugee camp. Fischer learns from one inmate, Wojkiech, that there is a smuggling operation into Germany called 'Star'. Fischer pays for Anna, the child, Wojkiech and himself to be taken back over the border using the 'Star' route. Fischer and Anna practice passing a weapon between them during searches to prevent it being found. They kiss.

Fischer and other refugees arrive at the German border in Poland. The guide asks them all to write postcards to their family, just like the one the nurse smuggled out. The refugees are taken through a hillside tunnel. It is dark and slippery, and the guide insists they all hold on to a rope against the wall. Fischer realises it has been electrified and shoots the guide. The tunnel leads to a cave where thousands of refugees have been murdered. They continue overland and reach Germany. Fischer is sure now that Eupol has been paying off the Mafia to stop the refugees entering Germany, and has turned a blind eye to the genocide. The murder of the nurse will increase security spending; much of it will end up in the Russian mafia's pockets. Fischer, Anna and the child stand in the middle of a highway at night, waiting for someone to stop and help them.