Kevin Costner Says He Cast Son Hayes, 15, in “Horizon ”So They Could 'Hang Out': 'Really Proud' of Him

The Oscar winner praised his son Hayes' "acting debut" in the upcoming two-part Western, in theaters this summer

Kevin Costner is beaming with pride over his son Hayes' big-screen debut.

The 15-year-old appears in his dad's upcoming two-part Western Horizon: An American Saga, and can be seen in the recently released trailer which Costner, 69, shared a snippet of on Sunday.

"When it’s your movie you get to pick who you hang out with 👍🏻," read the caption on the post, which was shared to the Kevin Costner & Modern West Instagram account. "Really proud of my son, Hayes, for making his acting debut in #HorizonAmericanSaga."

"And thanks to all of you for the love you’ve shown our trailer this week," Costner's caption continued. "I couldn’t be more excited to share this with you."

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Related: That's Kevin Costner's Son Hayes, 15, Making His Acting Debut in the Horizon: An American Saga Trailer

In the trailer, which dropped Feb. 26, Hayes stars in a tense scene that shows him helping a woman (played by Sienna Miller) and young girl, who are presumably his mother and sister, into a shelter through an opening in the floor as their home is attacked.

"It's all right — I'm gonna be with Dad," he tells Miller's horrified character, before closing the door on their hiding spot.

Costner — who co-wrote, directed and stars in Horizon — told PEOPLE in November 2022 that Hayes, who was 13 at the time, is "very good" in the film.

"Hayes plays the namesake character that I actually play in the movie. He's 13 years old and the screenplay's been around longer than that," said the two-time Academy Award winner.

"I kind of did it on purpose, so he could be hanging out with me," Costner added at the time. "I'm like any other parent — I'm trying to figure out, like, 'This is really neat. You should come be with me.' "

Related: Kevin Costner Unveils Trailer for Horizon: An American Saga, His Epic 2-Part Western

Per a synopsis, Horizon "explores the lure of the Old West and how it was won — and lost — through the blood, sweat and tears of many."

"Spanning the four years of the Civil War, from 1861 to 1865, Costner’s ambitious cinematic adventure will take audiences on an emotional journey across a country at war with itself, experienced through the lens of families, friends and foes all attempting to discover what it truly means to be the United States of America," the synopsis adds.

Aside from Costner, Hayes and Miller, 42, Horizon's cast also includes Sam Worthington, Jena Malone, Abbey Lee, Michael Rooker, Danny Huston, Luke Wilson, Isabelle Fuhrman, Jeff Fahey, Will Patton, Tatanka Means, Owen Crow Shoe, Ella Hunt and Jamie Campbell Bower.

Hayes is the middle child of Costner and ex-wife Christine Baumgartner, who also share son Cayden, 16, and daughter Grace, 13. Additionally, the Dances with Wolves actor is dad to daughters Annie and Lily, and sons Joe and Liam from previous relationships.

Horizon: An American Saga Chapter 1 is in theaters June 28, followed by Chapter 2 on Aug. 16.

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