Marathon runner is a online documentary of Minna, a young woman fond of running, who is diagnosed with breast cancer. The material has been filmed at the same time everything happened. The film shows Minna's and her spouse Timo's experiences and emotions through the different phases of the disease, treatment, and life. Minna does not give up her plan to run a marathon despite of the cancer.

Minna is a young woman in love with two things: running and Timo, her husband. She is diagnosed with breast cancer and faces the possible loss of both of her loves. Together with Timo they decide to film their ordeal, all the personal experiences and emotions. Minna does not want to give up and fights to follow her plans to participate on a marathon.