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.

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.

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.

In this video, physicist and author Harald Lesch talks about how Germany could phase out coal and nuclear power completely and still meet all of its energy needs.

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.

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

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...

Nico's friends surprise him with paella, one of his favorite Spanish dishes. They talk about homesickness, but Nico seems quite happy in Germany.

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

Selma is happy that her family will get to stay in Germany, but she still misses her homeland. She tells Lisa about some of the differences between Germany and Syria.

Germany is not a big enough country to devote all of its land to creating renewable energy – but there is another place with vast expanses of empty space and limitless sunshine.

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.

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.

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.

This small school in the federal state of Baden-Württemberg is quite unique in terms of the independence it grants its students... take a look!