Teenaged Astrid Lindgren (Alba August), who later went on to write the Pippi Longstocking series, leads a carefree life with her family in the forests and fields of rural Sweden. Restless and eager to break free from the confines of her conservative upbringing, she accepts an internship at a local newspaper where she attracts the attention of its married editor, Blomberg (Henrik Rafaelsen).
After Astrid becomes pregnant, she leaves her childhood home and goes to Copenhagen to secretly give birth to a son, Lasse, whom she reluctantly leaves in the care of a foster mother, Marie (Trine Dyrholm). Astrid goes into self-imposed exile in Stockholm, refusing Blomberg’s offer of marriage and saving up her paltry salary for visits to see Lasse. When Marie falls ill, Astrid uses her imagination and flair for storytelling to reconnect with her son. In spite of her struggles, Astrid emerges with a newfound courage that will later form the foundation of a vast and beloved body of work.