In "That Most Important Thing: Love," Servais Mont, a freelance photographer known for capturing scandalous images, becomes captivated by Nadine Chevalier. Nadine is a troubled actress struggling in the low-budget film scene, entangled in a marriage with a quirky collector of film photography. As Servais delves into Nadine’s world, he finds himself drawn to her complexity and pain, igniting a connection that challenges both their lives. The film explores the intersection of passion, ambition, and the often tumultuous pursuit of love amidst the backdrop of the film industry.