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.

Yara is surprised to see her nephew Nico at her shop, since she didn't realize he was in Germany. Nico, Tarek, and Yara decide to go have a meal at Tarek's restaurant and tell each other what happened.

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.

Tarek and Nico talk about what it takes to run a business. It turns out that Nico is good at fixing bicycles, just like his aunt! And suddenly, Yara arrives back at her shop.

In this Christmas comedy, Academy Award-winning actor Christoph Waltz plays a pet shop owner who generally prefers animals to people. Recently divorced, he is still very attached to his ex-wife – who lives right across the hall from him.

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...

Selma tells Lisa about her family's life in Syria. At this point, many of the people she knew have moved away.

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.

Nico arrives back at Inga's on crutches, but luckily with no broken bones. At the doctor's orders, he needs to take painkillers, use salve, and most importantly, stay off his leg – something he finds difficult to do.

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.