Martha develops a romantic relationship with Jonas Kahnwald in June 2019, but during Jonas' extended absence from school following his father's suicide, begins dating his friend Bartosz. After Jonas' return on November 4th, Martha joins Bartosz, Jonas, and her brothers Magnus and Mikkel in a late night escapade to find the missing boy Erik's hidden drug cache outside the Winden Caves. Following her brother's disappearance at the cave mouth, and her being torn between Jonas and Bartosz, she becomes increasingly sorrowful in the following days.
After ignoring multiple calls from Bartosz, Martha texts Jonas on the morning of November 7th, wanting to talk with him. After performing at the school play later that night, Jonas visits Martha in the dressing room. Jonas confides in her that he was in psychiatric treatment rather than an exchange program in France as Bartosz had been telling their classmates. Jonas then asks why she contacted him rather than Bartosz that morning, and she embraces him in a kiss.
Unaware that Jonas has traveled back in time to 1986, Martha unsuccessfully tries to contact Jonas multiple times during the next two days. On the evening of November 9th, Martha confronts Jonas in the pouring rain as he is leaving home. Jonas abruptly tries to leave, but she demands to know why Jonas kissed her only to ignore her afterwards. Now aware that Mikkel is his father, making Martha his biological aunt, Jonas rejects her tersely, unable to explain the impossibility of their relationship. Saddened and angered by Jonas' seemingly cold response, she reconciles with Bartosz after telling him about her meeting with Jonas. On Novermber 12, Martha breaks up a fight between Bartosz and Jonas outside the highschool-- the last time she will see him before he disappears. On June 27 2020 she is killed by Adam the oldest version of Jonas, in order for Jonas to become Adam, Jonas grieves over her death but just before the God Particle destroys Winden another version of Martha takes Jonas claiming she is from a different world.