Rolling Stone caught up with Metallica drummer Lars Ulrich to discuss his involvement in the new Netflix film, Triple Frontier.

He got involved with Triple Frontier — a movie about five ex-military men attempting to rob a Colombian drug lord — last fall when director J.C. Chandor called him out of the blue with the offer of drumming on the movie’s soundtrack. They’d met in 2013 after a screening of Chandor’s All Is Lost at the Mill Valley Film Festival. Ulrich was curious about the movie and asked the director a question during the open-audience Q&A. “When I met him after the screening, he said he recognized my voice,” Ulrich says. “It turned out he knew Metallica quite well and we stayed in touch.” Chandor told him that composer Rich Vreeland, who works under the name Disasterpeace, was working on the score but that he thought Ulrich’s playing “would contribute, embellish, elevate or add another layer,” according to the drummer.

“I was more concerned about the rhythmic element rather than the melodic element,” Ulrich says. “I was playing more to the pulse of the scene.”

The film stars Charlie Hunnam, Ben Affleck, and Pedro Pascal. Synopsis: Five former Special Forces operatives reunite to plan a heist in a sparsely populated multi-border zone of South America. For the first time in their prestigious careers, these unsung heroes undertake this dangerous mission for self instead of country. But when events take an unexpected turn and threaten to spiral out of control, their skills, their loyalties, and their morals are pushed to a breaking point in an epic battle for survival.