After her mother's death, Irja, an evacuee girl, finds herself in a poor financial situation. Working as a housekeeper for her former teacher on a starvation wage, her situation improves when she is hired as a janitor at a secondary school. Despite the opposition of Principal Kuusi, she decides to take the matriculation examination and, in order to improve her writing skills, responds to a correspondence advertisement placed by the mysterious Master Ahtojää.