Sasha Mezhevoy was five years old when she, her older brother and sister were sent to an orphanage in Moscow. They were told they were going to be adopted by a Russian family. But they were not orphans. They were Ukrainian children who had been forcibly removed from their father.

Sasha grew up in Mariupol, the port city that endured more than 80 days of bombardment in one of the bloodiest and most destructive chapters of the early months of Russia’s full-scale invasion.

The family became separated in April 2022 when the children’s father, Yvgeny Mezhevoy, was imprisoned in a Russian detention centre. After 45 days, he was released with no more explanation than with which he had been seized. He said that when he found out his children had been taken, “a bolt of rage shot through me”. Against the odds, with practical help and financial aid from a resourceful volunteer network, he recovered his three children and took them to the safety of Riga in Latvia.

Some months later, Sasha and her father were among the main subjects of a documentary about Ukrainian stolen children. But rather than depicting the story of their harrowing deportation or arduous rescue, the film-makers focused on their experience at an animal therapy retreat in the Estonian forest.

Sasha, who was seven during filming, spends her days at the retreat “interviewing” the women there in the hope that one will become her mother. Her real mother walked out on the family when Sasha was eight months old.

Between therapy sessions, the children walk golden retrievers, ride ponies in the verdant forest and swim in the Baltic Sea. Therapists hope the natural respite will soothe their souls and help undo some of the trauma of their separation in Russian custody.

The families in this film are unusual: only a minority of Ukraine’s stolen children have been reunited with their parents.

Ukraine’s government has identified 19,546 children who have been unlawfully deported or forcibly transferred to Russia since the start of the full-scale invasion in 2022. The government-backed Bring Kids Back initiative estimates 1,898 have returned from deportation, forced transfers and occupied Ukraine.

But researchers say the true scale of the removals is unclear as Russian authorities erase records and falsify identities. The international criminal court has issued an arrest warrant for Vladimir Putin and Russia’s commissioner for children’s rights, Maria Lvova-Belova, over the deportation of Ukrainian children to Russia.

In September, Volodymyr Zelenskyy accused Russia of a double crime against Ukraine’s children: “Russia first abducted them and deported them, and now it tries to steal everything they have inside – their culture, their character, their bond with family and their identity,” he said.

The documentary, After the Rain, does not tell this political story. The British director Sarah McCarthy, who has Ukrainian heritage, said she wanted to “introduce as many people as I could to these children as children, not as a statistic, not as a political story, just as kids with all their mischief and fun and longing”.

Veronika Vlasova, aged 14 in the film, is the other main subject. In one of the first sessions at the retreat, she is asked to draw herself and offers a blank, featureless face. She spent more than a year in Russia, where she experienced bullying, propaganda, interrogations and time on an isolation ward. She was released only after her mother, a Ukrainian military veteran, gave a speech to the UN security council in April 2023 denouncing her daughter’s captivity.

At the retreat, Veronika deploys jokes and irony as a defence. Counsellors believe she is suffering from depression and encourage her to let her guard down. But the time is short. “It is two weeks. It’s not going to be some miraculous recovery from all of the things that have happened to her,” McCarthy said. “But that was never their intention.”

The film, with its lingering shots of the Estonian wilderness, tells an emotional rather than political story. Neither the children’s bleak experiences in Russia nor the difficult and dangerous rescues by their families are deeply explored.

McCarthy has a very practical explanation: “The material that I had in my drives that went through my lens was about Sasha and Veronika’s experience of that animal therapy retreat. And the challenge for me creatively was to capture the emotions that took place.”

One scene in the film shows Sasha not long out of bed. The still sleepy girl asks one of the therapists: “Why don’t you want to become our mama?” It is a tender moment, as if both have forgotten that the camera is rolling.

After the Rain has had months of official screenings and now distributors are seeking broadcast deals to find a wider audience.

McCarthy said that during the shoot she and her crew lived through the same daily rhythm as everyone else. They ate together, swam together, talked when the cameras stopped rolling, meaning eventually “you just become part of the furniture at some point”.

The children could stop the filming at any time, a power over the adults they relished. “They stopped us continuously, especially at the beginning,” McCarthy said, which was frustrating at first but “was definitely for the best, because it just shifts the power dynamic in a way that is better for everybody”.