The author of several successful plays, she wrote some of them with actress Jane Cowl—most notably Smilin' Through (1919), which was adapted three times for motion pictures.

Later that year the two women began collaborating, often under pseudonym Allan Langdon Martin,[2] on a series of revivals of World War I melodramas.

[4] In 1920, director Laurence Trimble persuaded Murfin to purchase a German Shepherd dog—Strongheart—that became the first major canine film star.

[5][6][7] Strongheart starred in four films that Trimble directed from Murfin's screenplays: The Silent Call (1921), Brawn of the North (1922), The Love Master (1924) and White Fang (1925).

[1] Murfin's later screenwriting credits include Way Back Home (1931), Our Betters (1933),[10] The Little Minister (1934), Spitfire (1934), Roberta (1935), Alice Adams (1935), The Women (1939), Pride and Prejudice (1940), and Dragon Seed (1944).