Servais Mont (by Fabio Testi), a photographer, meets Nadine Chevalier (by Romy Schneider), an actress who earns her money starring in cheap soft-core movies. Falling in love with her, he borrows money from the loan sharks to finance the theatrical production of Richard III and gives Nadine a part. Meanwhile, Nadine is torn apart between Servais and her husband Jacques (by Jacques Dutronc), to whom she has moral obligations. That Most Important Thing: Love is an explosive melodrama, that explores the tension between passion and duty, as well as between art and trash.
Romy Schneider obtained the inaugural Cesar Award for Best Actress for this role.