In October 2016, a little movie shot on a budget of just $1.5 million opened in four theaters. Four months later, that movie — “Moonlight” — took home the Academy Award for Best Picture, and in doing so, launched the careers of several of its young, unknown stars.

Chief among them is 22-year-old Ashton Sanders, who played the teenage-version of the protagonist Chiron as he struggled with his sexuality. Sanders hits theaters again on Friday opposite Denzel Washington in “The Equalizer 2.”

In the sequel to the violent 2014 thriller, Washington returns as Robert McCall, a Lyft driver and vigilante with a serious thirst for justice, especially after a close friend of his is murdered. Sanders joins him as art student Miles, McCall’s neighbor who is beginning to get mixed up with the wrong crowd. In the film, the two characters form a father-son bond, which carried over off-camera.

“What you see on-screen is basically an extension of our relationship, like the love that’s there,” Sanders tells The Post. “Denzel has definitely become somewhat of a mentor to me through the process.”

Sanders grew up in South Los Angeles and got into performing through a conservatory for children of color before attending an arts high school. While studying at Chicago’s DePaul University, he landed his breakthrough “Moonlight” role and decided to drop out and take a chance on making a Hollywood career happen.

He still keeps in touch with his co-stars from that game-changing film via Instagram and texts. The other two Chirons have also kept busy — Alex Hibbert appeared in “Black Panther” and stars on the Showtime series “The Chi,” and Trevante Rhodes was in Jay-Z’s “Family Feud” music video in December and he’ll be in September’s franchise flick “The Predator.”

“All of the young actors in that film — that was our big break … So everything has been a whirlwind,” says Sanders. “I’m still getting used to it, and I don’t think I will.”

With a packed 2019, he’d better. He already has leading roles in two notable films coming next year: the sci-fi flick “Captive State” and an adaptation of Richard Wright’s classic novel “Native Son.”

Through it all, though, he’s focusing on something he learned from Washington.

“[He taught me] to trust my work and to never doubt myself when, factually, I just don’t need to,” says Sanders. “Denzel stripped that [self-doubt] away from me when he saw it while filming. I still carry that with me.”