Considered a prominent figure as one of China's "sixth-generation directors", Wang Xiaoshuai shot to international success with the film Beijing Bicycle, which won the Jury Grand Prix at the Berlin film festival in 2001. Most of his films examine social issues through the stories of grassroots people struggling at the margins of society.

So Long, My Son was conceived in 2015, when China relaxed its one-child policy, recalls the director.

"The news coincided with a story that I've been pondering over for a long time. I didn't think too much about festivals or the market then, but just wanted to produce a film which resonated with ordinary people," he says.

With a running time of three hours, the film charts the lives of two parents over the course of four decades, who move from a city in North China to a faraway village in East China's Fujian province to escape the sorrow of losing their son. The boy drowned after his best friend asked him to join his friends swimming in a reservoir on a hot day, and the accident left the two families inextricably linked through their sorrow and regret over the years.

Just like most of Wang Xiaoshuai's previous films, So Long, My Son bonds the individuals' fate and lives with the immense transformations taking place in China, making the story both wider and deeper in scope.