Thirty-something Parisian artist Billie is working towards her next exhibition when she receives the news that her mother, with whom she has had no contact for years, has drowned in the river near her nursing home. In an attempt to understand the circumstances of her death, she returns to V, the village where she grew up in the parched, sun-drenched hills above the Mediterranean.

When she arrives there, Billie finds herself reliving memories of another river drowning, 20 years earlier, memories she had tried to obliterate. What happened to Billie's dear friend Lila back then, at the age of 16, and why is Billie stalked by guilt?

Sunlight Hours paints a picture of three generations of women, united by the secrets of a river.