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German actor Sabin Tambrea, director Adolfo J Kolmerer and the Ziegler Film team behind Prime Video film Sebastian Fitzek’s Der Heimweg (The Calendar Killer) discuss adapting the thriller for the screen and the hidden theme behind the story.
For a large portion of filming on Prime Video feature film Sebastian Fitzek’s Der Heimweg, star Sabin Tambrea found himself alone on the set of his character’s apartment, talking into a phone with no one on the other end of the line.
It summed up the practical challenges of filming this adaptation of Fitzek’s thriller novel, in which Tambrea plays Jules, a volunteer working for a telephone support service that helps people, especially women, get home safely late at night.
On an otherwise uneventful evening, Jules receives a call from Klara (Luise Heyer), a young mother who claims she will die that night at the hands of a notorious serial killer who has given her an ultimatum: either she kills her husband Martin (Friedrich Mücke) or she will be murdered. Jules then becomes the only person who can help to save her from the so-called Calendar Killer.
Debuting on Prime Video worldwide today following its world premiere at last summer’s Monte Carlo TV Festival, the project marks the second collaboration between author Fitzek, producer Ziegler Film and the streaming platform following 2022 six-part series Sebastian Fitzek’s Die Therapie. Ziegler’s Regina Ziegler, Barbara Thielen and Susa Kusche return as producers for Der Heimweg (which translates into English as The Way Home), with Susanne Schneider writing and Adolfo J Kolmerer directing.
“The main pitch is a woman calls The Way Home line that we have in Germany, which is based on a real service that we have where women call it at night to walk home with somebody on the phone to feel safe,” Kolmerer says. “The pitch that Sebastian wrote in his book is about a man who works at this service, and he gets a call from a woman in distress who’s being chased by the Calendar Killer, who has killed at least three people in Berlin.
“This man on the phone line needs to help her. But she wants to kill herself, too, because she’s been a victim of domestic violence. So the movie is a Trojan horse to talk about the subject of domestic violence as well.”
Delighted at their first collaboration, Fitzek was more than happy to reunite with Ziegler Film for Der Heimweg, which he says has remained very faithful to his original novel.
“For me as an author, the most important thing is you stay true to the core of the books, to the protagonist and to what the story is about,” he explains. “There are some benchmarks in each of my books. If you stay true to them, you can change a lot in between.
“Adolfo managed to create a different version, but it’s so close that I would bet all my fans are going to love it. It’s the book but it’s different – and different in a positive way. It’s really a movie that is worth watching twice.”
Thielen picks up: “You can always ask him what he thought about the characters, what he thinks about what we’re changing. He’s a very good partner.”
“He’s very open to changing something,” agrees Kusche. “Often writers really try to save their babies so much, to keep the story as it is in the book, and it’s really not helpful, not for them or the movie. This is something we really appreciate. Sebastian is very professional in this case and it makes it much easier to work with him.”

That the film is being produced for Prime Video, as opposed to a German broadcaster like ARD or ZDF, means the creative team could also push the boundaries of the story. “Sebastian’s thrillers have some violence and sex, and you can tell it freely [on Prime Video],” Thielen adds. “It’s easier to tell these kinds of thrillers for a streaming platform.
“But we always have lots of discussions about what is best for every book. Not every book from Sebastian works as a series. Some are better as a series, some are better as a movie, so that was the main decision.”
As Der Heimweg takes place over a single night, the story proved to be a natural fit for a feature. “But Sebastian writes so much, I could do a show out of it,” Kolmerer jokes. “He allowed me to keep some things but I could run with it. I would do it again tomorrow. It was a pleasure.”
The director praises Tambrea’s performance, though the actor hadn’t previously read the novel before landing the part of Jules. “I was sent the script and it was absolutely clear to me that I wanted to be a part of it, because it was a huge challenge to have an entertaining movie dealing with an important and delicate topic,” he says. “We wanted to bring this topic into discussion with high budgets and a first-class movie. That was the approach and I think we made it.”

For 18 days of the shoot, he was alone on set. “We shot in the studio and sometimes he was the only actor there,” Thielen reveals.
“The first half of the movie, we shot in the studio, as we built the set there – 60% of the movie plays in Jules’s flat,” says Susche. “It was a very good decision to build this set as it gave Adolfo freedom to create the atmosphere and to have these intense moments. Then at the end we shot two weeks at night in the woods. It was very cold, very hard. It was quite a challenge.”
“It was an amazing challenge for the actors,” says Kolmerer. “It was also [a challenge] for me to prepare for it. It was complicated. He’s on the phone, she’s on the phone, so I shot 18 days with him, then 12 days with her. She’s running through Berlin, it was below zero. It was very interesting.
“Because I shot [Sabin] first, I knew what he did so I could tell Luise and she could react. It was a completely different way of working.”
Fitzek is so impressed by Der Heimweg that he compares it to works by Alfred Hitchcock or Brian de Palma, such is the claustrophobic nature of the film, despite the fact Jules is given relatively little to do.
“Usually when I write something, you have a little action so the actors can do something. But I put him in a flat with a telephone – you don’t even see the woman at the other end,” he says. “This could have gone terribly wrong; it could be so boring. And it’s brilliant.”
Yet while the thriller elements of the film will likely hook viewers, the fact the story is actually about domestic abuse is never far from the surface in this multi-layered production. The key to that part of the story is Heyer’s performance as Klara, a character described as a “strong victim” who is never a cliché.
“We wanted to portray a woman differently,” Kolmerer says. “She’s a victim of domestic violence and she has a type of schizophrenia. She’s saying no one believes her, and one of the main issues today is we don’t believe the victims. We wanted to portray her as strong because I wanted people to root for her and not say, ‘Oh my God, she’s so annoying.’

“We got Luise and it was very hard for her. We talked for a long time on the phone and she said, ‘How can I play the weakest character without losing the audience?’ She was always like a chameleon. It was very ambiguous. I think she did great.”
The cast and crew spoke to real victims of domestic abuse to ensure the film is as authentic as possible when portraying the subject and answering the question of why Klara hasn’t left Martin. The phone service Jules works for is also closely modelled on a real service in Berlin.
“Normally when you see a husband who abuses their wife, you always see the drunk guy, the wife beater, and you’re like, ‘Why doesn’t she leave? She should be leaving,’” Kolmerer says. “But when we were doing research and listening to real victims, this person [the abuser] could be your best friend. So we really went out and cast one of the most handsome and nicest dudes in Germany, who actually told me on the phone, ‘I don’t know how to play this.’”
“Besides the entertainment, if you search for a message, to me it’s to stop disbelieving,” Fitzek adds. “You don’t have to believe anybody who claims anything but we live in a society where you start to disbelieve [someone] if something doesn’t fit your expectations. [Victims] feel ashamed to talk to their inner circle and they aren’t believed because [other people] think in clichés. This is the thing that makes it so hard for women to speak up. They feel they are the only ones on earth. An entertaining piece of art has the power to show you’re not alone.
tagged in: Adolfo J Kolmerer, Prime Video, Sabin Tambrea, Sebastian Fitzek’s Der Heimweg, The Calendar Killer, Ziegler Film