The second of the three Nielsen children, Martha is a sensitive girl who loves acting. She was cast in the leading role of the school play. Martha is in a relationship with Bartosz Tiedemann, but she actually loves someone else: Jonas Kahnwald.
The disappearances of her brother Mikkel and her father Ulrich tear her apart. This damages her relationship with her mother Katharina, but she remains close to her older brother Magnus.
A timeless love
In the summer of 2019, it looks as though Martha and Jonas are going to become a couple, but his father's suicide shakes him. He spends months in therapy and stops answering her texts. Martha believes Jonas is in France and starts dating Bartosz instead.
When Jonas returns, their love is rekindled. That's until Jonas finds out Mikkel is his father, making Martha his biological aunt. Without giving her any explanation, Jonas blows her off and vanishes from Winden completely.
Bartosz and the time machine
Martha can't stop thinking about Jonas. She stays with Bartosz, but breaks up with him in the summer of 2020. She can't shake the feeling that he's hiding something from her.
Not long after, Martha, Magnus, and Franziska and Elisabeth Doppler find Bartosz in the Winden caves with a strange device. They overpower him and tie him up until he tells them what he's doing.
When Bartosz reveals he has a time machine, they don't believe him. Bartosz proves it by traveling with them to 1987. He tells the others about Noah and how things have happened exactly as predicted. Noah also prophesied that Jonas would return.
Martha and the Stranger
Martha feels even more hopeful about Jonas' return when she discovers a silver St. Christopher pendant on her pillow. She'd given it to Jonas in the summer of 2019. As it turns out, the Stranger is the one who left it for her.
Not long after, they meet one another. The Stranger reveals to Martha that he is Jonas and they share a moment of closeness before Katharina Nielsen interrupts. She tells Martha that the Stranger is actually her daughter's own nephew, leaving Martha distraught.
In the future, Jonas finds a wooden cross in the cemetery with Martha Nielsen's name on it. He makes it his mission to prevent her death, even 30 years later. On the day of the apocalypse, the Stranger forces Martha into the bunker at gunpoint where he thinks she'll be safe.
But he leaves her there alone and Martha manages to escape. She is looking for the young Jonas and finds him at the Kahnwald's house. They kiss. Adam suddenly appears and shoots Martha. Jonas is left in utter desperation. The pain is what's necessary to turn Jonas into the man he will become – Adam.