STXfilms has closed a deal to premiere its upcoming movie “My Son,” a thriller starring James McAvoy and Claire Foy, on both Peacock and The Roku Channel.

As part of the deal, which was negotiated by David Spiegelman for STX, the two online services will share rights to “My Son” throughout the year. The film will premiere first on Peacock on Sept. 15 on its free tier. Months later, it will leave the NBCUniversal’s subscription-based service and be available to stream for free on The Roku Channel in the U.S. starting on Dec. 15.

The film’s release deviates from traditional streaming windows, in which one digital platform would house a new title for a set period of time. “My Son” was initially set to debut only on Peacock, but the movie’s backer STX later forged the pact with Roku to maximize profits.

“We’re thrilled to have worked with Peacock and Roku on this bespoke deal that uniquely tailors everyone’s needs and maximizes value for all three companies and our talent partners,” said Adam Fogelson, the chairman of the STXfilms motion picture group. “The real winners are the Peacock and Roku audiences, who will have the chance to see a daringly original, star-driven movie on the platform of their choice.”

“My Son” follows a man (McAvoy) who travels to the town where his ex-wife (Foy) lives after their only child goes missing. McAvoy’s role was entirely improvised; he wasn’t given a script or dialogue in an effort to evoke an honest portrayal of a person whose life is clouded by mystery. “My Son” is a remake of Christian Carion’s 2017 French film, which was similarly ad-libbed. Carion is writing and directing the English-language adaptation as well.

“Since we started The Roku Channel in 2017, we’ve worked with strategic partners who help us deliver on our goal of bringing viewers compelling, best-in-class entertainment in a free, ad-supported environment,” said Rob Holmes, Roku’s VP of programming. “We’re excited to be partnering with STXfilms to deliver even more great programming, like ‘My Son,’ to users of The Roku Channel.”

“My Son” is produced by Carion, Laure Irrman for Une Hirondelle, Vincent Maraval and Brahim Chioua for Wild Bunch International, Rebecca O’Brien for Sixteen Films, and Marc Butan for Mad River Pictures. Mad River International represents the film’s foreign rights.