EXCLUSIVE: Sinqua Walls has been cast in Client Eastwood’s upcoming biopic The 15:17 To Paris from Warner Bros. and Village Roadshow. It’s based on the novel The 15:17 to Paris: The True Story of a Terrorist, a Train, and Three American Heroes by Anthony Sadler, Alek Skarlatos, Spencer Stone and Jeffrey E. Stern about the 2015 thwarted terrorist attack on Thalys train #9364 bound for Paris.

Dorothy Blyskal penned the screenplay that follows the course of  the friends’ lives, from the struggles of childhood through finding their footing in life, to the series of unlikely events leading up to the attack. Walls will play Marine Chris O’Neil.

The pic will feature the real-life heroes, Salder, Skarlatos, and Stone, portraying themselves, as well as Judy Greer, Jenna Fischer, Ray Corasani, Paul-Mikél Williams, Max Ivutin, Bryce Gheisar, Cole Eichenberger and William Jennings.

Eastwood is producing with Tim Moore, Jesssica Meier, and Kristina Rivera. Bruce Berman is serving as exec producing of the film, which is currently in production.

Walls recurred as Sir Lancelot on ABC’s Once Upon A Time, and has appeared in previous seasons of MTV’s Teen Wolf  and Power on Starz. He’s repped by APA and Zero Gravity Management.