While Johannes spies on his ex-wife and her new boyfriend at the Christmas market, Sascha confronts him about the promises he made.

Sascha reveals to Johannes, who is dressed as Saint Nicholas, that his parents are on the verge of separation. Later, Johannes spies on Marion and her new boyfriend at the Christmas market.

To earn some money and help out his injured employee, Johannes visits several families pretending to be Saint Nicholas – and ends up making quite an impression.

When Marion comes by to help Johannes with his taxes, he finds out she's met someone else – news he doesn't deal with particularly well.

Johannes asks his new employee, a psychology student, about love and relationships – but doesn't particularly like the answer he gets in return.

Petri's colleague is arrested, and Petri and his wife make amends. It's time for Julius, the young runaway, to say goodbye to Harry and go home – but Dirk has one last surprise.

While Dirk bonds with the young runaway, Katja figures out what actually happened at the Harms company.

Konstantin, the new temp worker at the pet store, wonders why he's even needed considering how little money the store is making. Meanwhile, owner Johannes uses the store's problems to try to bring his ex-wife Marion – who also happens to be his neighbor – back into his life.

Katja and Dirk arrive in time to stop Mr. Petri's madness and bring him in to the station. Meanwhile, Lothar finds out the truth about their supervisor.

Henning finds a potential lead regarding the runaway boy's identity, while Petri turns up at his former workplace yet again – this time armed.

Henning shows up at Harry's to discuss the problems he's experiencing in his relationship, and is disappointed when Harry expresses the same opinions as his girlfriend. Then the doorbell rings...

Walter Petri refuses to believe that one of his designs could have been flawed, and is furious at his wife for talking with the company's boss behind his back.

At the station, the group tries to figure out whether Küppers is actually pregnant and where the young runaway came from. When Walter Petri returns to work and locks himself in his former office, the real reason for his early retirement is revealed.

At home with Harry, the runaway finally speaks. Meanwhile, Walter Petri follows Dirk's advice and returns to his former office – but he doesn't like what he finds there.

After Henning's mistake, the group finds the young stowaway hiding in a dumpster. Meanwhile, Lothar uncovers new information about Superintendent Küppers.