My Mother’s Wedding follows three sisters, Katherine, Victoria, and Georgina, who come together for their mother Diana’s nuptials. The girls’ fathers, Diana’s first two husbands, were both navy pilots who died in devastating plane crashes, losses they all continue to grapple with. Katherine (Scarlett Johansson), the eldest daughter and a navy captain, remembers the most about them. Victoria (Sienna Miller), an irreverent actor, reluctantly leans on the deaths for media fodder. Georgina (Emily Beecham), the youngest, finds herself in a complicated state of self-pity. None feel quite ready to embrace their new stepfather, nor Diana’s newfound happiness—try as she might to remind them that their fathers, however enshrined in their memory, were flawed, as we all are.

Scott Thomas, who plays Diana, reports that working with Johansson, Miller, and Beecham on the film “was like driving a very fast, fabulous car with millions of buttons. They would just turn on the sixpence and be completely brilliant and take notes and sometimes argue back, and it was great.” Directing for the first time, she adds, “was thrilling, terrifying, exciting, and I’ve never been so happy in my life.”

Though fictional, My Mother’s Wedding, cowritten by Scott Thomas and her husband, the journalist John Micklethwait, is keenly introspective, coming from a deeply personal place: Scott Thomas’s own father and stepfather were both navy pilots who died in similar crashes when she was 5 and 11 years old, respectively. “I realized about eight years ago that my little brothers had absolutely zero memory of their father, and I, being the eldest of five kids, was the sort of keeper of the memory,” she says. Scott Thomas recalls treating this trauma as a precious thing: “You hang on to it and keep it for yourself, and you’ll not let anyone else have a go with it. But until you do that, you can’t really move on.”

Scott Thomas’s recent work as counterintelligence agency director Diana Taverner in the Apple TV+ spy thriller Slow Horses followed her return to the UK after many years living in France. Moving to Paris as a teenager, she had quickly fallen in love with the French way of filmmaking: “I love making tiny little films with 30 people, including the cast, on the call sheet,” she says. So, for her first project as a director, Scott Thomas set out to create the same coziness on her set, setting up base camp near the house where filming took place. “What happened was the three actresses, who I would always call ‘the girls,’ got closer and closer,” she says. “In the end, they started to kind of look like each other.”

Interspersed throughout My Mother’s Wedding are a series of animated vignettes, fragmented memories Scott Thomas has of her fathers. They were a collaboration with Iranian artist Reza Riahi, who hand-painted the scenes on glass. “They have that beautiful delicacy and slight transparency that is so gorgeous and very difficult to re-create,” she says. She began with these precious mini films, allowing the rest of the movie to grow from there.