He might be biased, but Zhang Yimou is unwavering in his assessment of his latest movie, Coming Home. "Gong Li really delivered the performance of her life," he says quietly, when we meet in a hotel in Cannes, away from the hullabaloo of the world's most prestigious film festival where his work has just played out of competition. "I thought, it's a great pity," he sighs. "Not for myself but for the actors … I felt they deserved to be in official competition."
Zhang has previously competed three times in Cannes, with Ju Dou (1990), To Live (1994) and Shanghai Triad (1995). To Live even took a share of the Grand Jury Prize, along with Nikita Mikhalkov's Burnt by the Sun, and Shanghai Triad was awarded a technical grand prize. But in many ways, the mainland filmmaker's fared better away from this festival - with two Golden Lion wins in Venice, with 1992's The Story of Qiu Ju and 1999's Not One Less, while memorably beginning his career with a Golden Bear in Berlin for his 1987 debut Red Sorghum.
Red Sorghum was also his first collaboration with Gong - whom he discovered when she was still a student at the Central Academy of Drama while he was a recent graduate of the Beijing Film Academy. Remarkably, they worked together seven times in the next eight years - including on the Oscar-nominated Raise the Red Lantern - during which time they became, respectively, China's pre-eminent director and actress. Their professional relationship evolved into a romantic one, only for both to unravel on Shanghai Triad.
It would be a decade before they reunited on 2006's Curse of the Golden Flower, by which point Zhang had moved into more commercial territory with martial arts spectaculars Hero and House of Flying Daggers and Gong had made her first foray into English-language cinema with Memoirs of a Geisha and Miami Vice. Now, eight years on, they're back for their ninth collaboration. "It's like meeting an old friend," says Zhang with a smile.
Or, to borrow from the title of their latest film, is it like coming home? "Actually, I've never really left home," says 48-year-old Gong, as she sips a latte. "Even through all these years of not doing a film with Zhang Yimou, I was always watching his movies and was waiting for a really good chance to collaborate again."
What they wanted was a real challenge and this tale, adapted from the final 30 pages of Yan Geling's novel, The Criminal Lu Yanshi, was certainly that.
For the 62-year-old Zhang, it was the chance to scale back after his last film, 2011's The Flowers of War - also based on a Yan Geling novel - which starred Christian Bale and proved to be the most expensive Chinese production at the time. In tone and feel, this latest film harks back to earlier, simpler works like 1999's The Road Home. "After the big glamorous movies I did in the past, going back is actually a challenge," he admits. "Coming back to your roots is extremely difficult."
Yet the real obstacles were for his star. "Even before starting up this film, Gong Li said to me, 'If I can manage this role, then I will be a truly great actress'," says Zhang.
"Any given actress probably wants to go one of two ways - to be extremely glamorous on screen or to be the opposite, which is extremely different or ugly. But the most difficult is to act [like] someone in the middle, just like any other person. So that's the biggest challenge for any actress - to be that level, to deliver that performance."
In this drama, she plays Feng Wanyu, a middle school teacher married to college professor Lu Yanshi (portrayed by Chen Daoming), who years earlier was sent away for "re-education" for his political beliefs. The film begins in China in the early 1970s, midway through the Cultural Revolution, with a dramatic sequence involving Lu's escape and return to the family home, only for their daughter Dandan (newcomer Zhang Huiwen), who barely knows her father, to turn him in.
Yet this is just the beginning, for Coming Home is not so much a politically charged piece but a melodrama of the heart. Years later, when Lu is exonerated and released, he returns home to discover that his wife has amnesia, possibly caused by a blow to the head that occurred on the day of his recapture. Unable to recognise her husband, Feng sees him as a complete stranger despite his best attempts to invoke old memories of their relationship with photos, letters and music.
As part of her preparation, Gong visited a hospital that cared for patients suffering from similar traumas to her character. "I went to see them every day for more than one month, to see them, to talk to their family members, to observe their reactions, their movement, their emotions," she says. She even spent time with director Huang Shuqin, with whom she made 1994's A Soul Haunted by Painting, who'd experienced "the same illness as Wanyu in the film".
Still, it's a high-wire act for the actress - from having to convince audiences that her character can no longer recognise her husband to ageing dramatically across the film and looking less than glamorous. "This is not like a normal movie," she says. "Zhang Yimou is very good at making movies for women, a story of a woman's love. But this time, in Coming Home, it is not Wanyu who is coming back but the husband."
Zhang concurs, noting there is something unique about the story, that it deliberately wears its heart on its sleeve. "The modern life in China now ... the couple, husband and wife, we will not talk about our love; we will think about the children first. Because normally we have 'one family, one child'. So really the kid is the centre of the family, but in this movie, it concentrates on love."
Ironically, Zhang recently fell foul of China's one-child policy when he and his wife Chen Ting, 32, admitted to having two sons and a daughter.
"It's the policy for everybody, so just like censorship you can't go around it," he says, cautiously. "A lot of people in China, how they get around it is to have children born outside of China. But because I'm so busy making movies all the time I didn't do it. A policy is a policy and I pay the fine."
Still, given the early success of Coming Home, the 7.5 million yuan (HK$9.4 million) fine shouldn't prove too traumatic. The film has already proved a huge hit in its home territory, grossing 82.4 million yuan in its opening weekend.
For all of the dramatic clumsiness that a story about amnesia can bring, it provides a useful analogy for those who experienced the trials of the Cultural Revolution and the denial of a past too painful to recall.
"Every household in China at that time was affected by the Cultural Revolution," says Zhang. "It was always tragic." Yet part of the success of Coming Home on the mainland, he says, is the way it's helped the younger generation understand the impact of the Cultural Revolution. "The movie really inspired parents to open up and tell their children what really went on," Zhang says. "A lot of young people ended up talking about what they'd heard and what their family had done."
If that's the case, it may prove to be one of the most important films of his career.
Coming Home opens on June 12