Black Dogs

In 1946, June and Bernard set off on their honeymoon. Fired by their ideals and passion for one another, they had planned an idyllic holiday, but in France they witness an event that alters the course of their lives entirely. Forty years on, their son-in-law is trying to uncover the cause of their estrangement and is led back to this moment on their honeymoon and an experience of such darkness it was to wrench the couple apart.

Synopsis from Open Library.