Directed by Italian filmmaker Luca Guadagnino, the English-language drama follows Marianne Lane (Swinton), a David Bowie-esque rock star who, after possibly career-ending vocal surgery, retreats to an island getaway with her lover (Schoenaerts). Upon arrival, the couple gets a surprise visit from Marianne's former flame, record producer Harry Hawkes (Fiennes), and his precocious daughter, Penelope (Johnson). As red wine flows and clothes come off, the four become entangled in a complicated web of sex and secrets with ultimately fatal results.
Reading the script for the first time, "I was captivated by how intricate these four characters are, and how they mix and match and intertwine," Johnson says. In Penelope, she sees a woman "who is hyper-intelligent and hypersexual, and finds amusement in playing with people's emotions and relationships. She's a scary young girl and does some pretty (messed-) up things to people, and thank God she suffers the consequences."
Johnson, 26, signed on for Splash just a week before it started filming on the remote Italian island of Pantelleria in 2014, replacing Margot Robbie, who dropped out. But when she jetted to the Sicilian coast for a table read, she initially second-guessed her decision.
"It was so last minute," Johnson says. "I just didn't feel like I was capable of doing it, and I felt like I had wasted everyone's time. I told Luca, 'I'm so sorry, I really don't think I can do this film.' Then Tilda sat me down and was like, 'This is going to be OK, you are going to be fine. We will take care of you and you are capable of doing this.' And I was like, 'OK.' "
Because of the island's arid, rocky terrain and jellyfish-infested waters, Splash's two-month shoot wasn't the vacation paradise it appears to be in the film. As a result, "we all became pretty close," Johnson says. "There really wasn't much to do, so we'd just play cards and watch movies."
Johnson is filming the next two Grey installments: Next year's Fifty Shades Darker and 2018's Fifty Shades Freed. "We're shooting them simultaneously, which is (confusing), but it's going really well," she says. Afterward, she'll reunite with her Splash team for two more films: music drama The Sound of Metal, with Schoenaerts, and horror thriller Suspira, directed by Guadagnino and co-starring Swinton.
"It's weird," Johnson says with a laugh. "I can't stay away from these people."