Michaëlis' most famous novel, The Dangerous Age (Danish: Den farlige Alder), has been championed as a groundbreaking work on women's rights.

She was the daughter of a telegraph official and noted Freemason, Jacob Anthonius Brøndum (1837–1921), and Nielsine Petrine Bech (1839–1932).

[2] She was brought up together with her younger sister, the later philanthropist Alma Dahlerup, in their modest home in Randers where her mother contributed to the family's meager income by making wreaths.

[5] Stangeland was unhappy with the literary and political activities of his wife, who had recently experienced a breakthrough as an author with The Dangerous Age.

It is the story of Elsie Lindtner, who, after divorcing her husband, attempts to rekindle a relationship with a younger man who had once worshipped her from afar.

The book created a great sensation, because it began to cut through tabooed themes like the sexual desires of a 40-year-old woman.

In these novels for adolescents, readers meet the stationmaster's daughter Bibi, who is motherless but enjoys some freedom as a result.

She is an idealistic tomboy who goes on train excursions on her own (with a free ticket due to her father's job) and fights ceaselessly for animal causes.

Translators of Bibi include the English poet Rose Fyleman and Austrian novelist and dramatist Maria Lazar.

[14] From 1933 on she took in German emigrants on her property in Thurø, including Bertolt Brecht and his wife Helene Weigel and their friend Maria Lazar, who remained in Denmark until 1939.