When he directs his own movies, Waller says his mixed culture is an asset. “I am Western-minded in most ways, but the rich Thai culture has not escaped me.” Which is why his films are social and cultural documents about Thailand, informed by an international perspective. Examples include Sop-Mai-Ngeap (Mindfulness and Murder) about a murder in a Buddhist monastery, and Petchakat (The Last Executioner), a biopic about Thailand’s last prison executioner. Both created waves at international film festivals and were nominated for many local awards.

And now The Cave, which is imbued with Thai mythological and religious motifs. Thanks to his Buddhist and Catholic background, Waller states, “Spirituality is an important part of me, and it translates into all my work, including The Cave. I personally feel that it is time we erase all barriers and walls that divide us—The Cave is very much about that. It’s not really about the boys but about the rescuers—those who came from all over the world and sacrificed their time and risked their own lives to help rescue a group of kids they had never met before. The biggest challenge was to get the details as accurate as possible. In the process, we received threats and experienced obstacles and rejections. We were basically pushed around just because we wanted to make a film about this particular event.”

However, giving up is not in Waller’s nature. When allowed only one day to shoot in the actual cave, he found another near the Thai Cambodian border as a double. But he confesses that the last sequences of the boys being taken out of the cave were some of the most challenging he’s ever done and how proud he was of his Thai technical crew. “Ultimately though, the film carries a message about how different people from all over the world can come together at a moment of crisis. It is a call for unity, that’s the most important thing.”

See also: What We Know About The Upcoming Film About The 13 Wild Boars