Her prize-winning 1943 historical romance novel Sunshine Follows Rain was adapted into a 1946 film of the same title.

After working as a subject teacher and lecturer at Bromma kommunale flickskola from 1931 to 1940, she worked as a lecturer at Bromma högre allmänna läroverk from 1940 to 1947[2] and from 1947 at Nya elementar in Stockholm.

Her breakthrough came in 1943 with Driver dagg, faller regn, with which she won a novel prize competition organized by Hemmets Journal, the book publisher Wahlström & Widstrand and SF Studios.

[4] Söderholm was a member of the pro-Germany Riksföreningen Sverige-Tyskland, and then also of the Swedish Opposition, and Jan Myrdal, who was her pupil at Bromma läroverk, described her as "a great admirer of Hitler".

[5][6] Her political sympathies appear in two of her books: Dit du går (1946) and Möte i Wien (1951).