Agatha Christie’s Endless Night is one of her most intriguing works – whether you like the novel or not, there’s something undeniably haunting and adult about her tale of the tragic young couple, and in the growing sense of unease that surrounds their new home, Gypsy’s Acre. With its youthful protagonists and non-formulaic structure, it’s no surprise that the novel was filmed just four years after its release, and in the early 1970s at that.