John Lee, the director of photography, shot Rachel's scenes differently from those of the other characters. Rachel was given central framing, with the camera low to give her an appearance of power and dominance, but there is also a lot of space in the frame to showcase her loneliness.
John Lee, the director of photography, said that during prep with Sandra Goldbacher, the director, they spoke a lot about trying to be honest about the 1950s but also modernizing it. They spoke a lot about being inspired by Hitchcock.
Pathologists read Agatha Christie novels to help them solve real-life poisoning cases. Christie was a poison expert; a skill she gained while volunteering at the dispensary in her local hospital during the First World War.
Agatha Christie was also involved in archaeology. She spent two decades living on excavation sites in the Middle East, writing novels and helping her husband on digs - often cleaning the finds with her face cream to preserve their moisture. She became an expert photographer during this time.
Trisha Biggar, the costume designer, used original costumes from the 1950s. Eleanor Tomlinson said one of the blouses she wore was even hand painted.