Oluwaseun Babalola remembers the exact moment she started to worry about her sister. It was 14 August 2018 and she was sitting on a sofa in a friend’s flat in Queens, New York. She had spent 10 days trying to get hold of Massah KaiKai, who had been due to travel from Sierra Leone, where she lived, to visit her in the US.

The sisters messaged or called each other every day, often multiple times. “We talked about everything and nothing. I would come home to a bunch of voice notes. She would vent or have something very funny to say – she was a very funny person,” says Babalola.

KaiKai’s silence had been “very weird” but Babalola had tried to rationalise it – maybe she was in a remote part of Sierra Leone; or had lost her phone. Even when someone answered her sister’s phone but said nothing, Babalola didn’t panic. “I thought, maybe it’s her but her phone isn’t working.”

But as yet another text went unanswered that afternoon in Queens, anxiety started to take hold.

Their mother, Ayodeji Babalola, was also becoming increasingly concerned. “We were calling, calling, but couldn’t reach her,” says Oluwaseun. After several weeks, Ayodeji flew to Sierra Leone while Oluwaseun stayed in New York, where she works as a film-maker and TV producer.

She told herself she needed to stay for work; in retrospect she thinks she was avoiding confronting the reality that KaiKai, 40, had disappeared.

“I think emotionally and mentally I was in a weird place and hoping I didn’t have to go. I was scared to go. It would make it real and I didn’t know if I had the emotional capacity to deal with it – not just being in Sierra Leone but dealing with my mother’s emotions too – I was just very frozen.”

Her mother sent the names of detectives she had spoken to in Sierra Leone, and Babalola would email them but received scant information back. “She [my mother] was taking photos of the detectives, the offices, the handwritten witness accounts – she was like a super sleuth.

“We printed photos in a local paper in Freetown but there was a lot of confusion – we were trying to figure out strategies; who we could reach out to,” she says.

KaiKai’s phone was found in Sierra Leone after a man called Ibrahim Mansaray who worked for KaiKai was arrested in connection with her disappearance, but the screen had been smashed so it was impossible to access. Babalola suggested the police ask the service provider, Africell, to track the calls; as far as she knows they didn’t.

It felt like every possible lead was being rebuffed. Babalola decided to join her mother in Sierra Leone to search for answers. But the authorities seemed unwilling to share any information with them.

In 2019, the investigation seemed to peter out. “By 2020 I was feeling pretty helpless. Massah had friends in Sierra Leone but some had left the country; everything was whispers and rumours. I thought about hiring private investigators.”

Babalola returned to New York and tried to pick up her life. She moved to a different city, looked after her mother, kept working. She no longer knew who to contact for updates in Sierra Leone.

Months passed, then one day someone posted a story about a trial on Facebook. According to a local news report, Mansaray had been sentenced to 50 years in prison after confessing to KaiKai’s murder and unlawful burial. No one had told the family that the trial was under way. Remains had been exhumed from the estate where she lived, but were never repatriated and without DNA confirmation in the US, the family say they cannot be sure it is her. In their eyes, KaiKai is still missing.

Babalola says there were multiple reasons they were in the dark over so many aspects of the case. They did not know anyone in the country, did not have the money to keep travelling to Sierra Leone or to hire a lawyer and what little information they gleaned seemed to contradict their own inquiries. At the same time, they were trying to “hold it together” to keep the rest of their lives on track while grieving, all during the Covid pandemic. “There are so many elements – you are in the middle of a tornado,” she says.

“The political climate [in Sierra Leone] can be difficult to grasp from the outside. Every effort I’ve made has been in pursuit of truth, however painful, so that whatever the outcome, especially if there are remains [that belong to KaiKai], there can be some form of resolution for our family.”

This year, Babalola released a short film called Fighting Giants about the attempt to find KaiKai. The film follows Babalola and her mother, played by actors, over one day, as they attempt to piece together what happened.

Much of the script is based on conversations they had with the authorities – including the attorney general and police. But there are also fantastical elements: a ghostly figure appears on the road as they take a tuk-tuk through the city.

“My background is in documentaries and I could have made a purely factual film – but I wanted more freedom to show how grief might manifest visually,” says Babalola.

KaiKai was eight years older than Babalola and felt “like a second mother” when they were growing up. “In photos I was always on her hip – she was always carrying me like I was her baby. I don’t think that was expected of her, I think she naturally took care of her little sisters – she looked out for us and was very motherly in that way.”

As adults, their relationship shifted on to a more equal footing and they became close friends. They were similar in many ways, creative and dynamic, and more extrovert than their middle sister, Ifeoluwa Babalola.

The three girls were born and raised in the US but their parents ensured they felt like proud Sierra Leoneans too. If they ever doubted themselves, their mother would remind them of their heritage. “Being African was always a positive thing – any doubts I had, my mum would say, ‘You know who you are and where you’re from, you’re an African child and you’re my child.’

“I think our parents tried to instil courage and confidence because they knew how discouraging the world can be.”

It worked. The sisters pursued their dreams – Oluwaseun went into film-making in New York, Ifeoluwa became a musician and KaiKai moved to Sierra Leone to launch a business that combined her love of fashion with her entrepreneurialism, employing women “to bring African fashion to the US”.

She collaborated with American Apparel on a limited edition T-shirt collection. Before her disappearance she had been due to become executive chair of the Small and Medium Enterprise Development Agency in Sierra Leone.

Making a film was an obvious response for Babalola. “I am a film-maker, that is how I express myself,” she says. But it was also a way of exploring the misogyny she and her mother encountered from the authorities. “I was met with a lot of resistance. It felt very patriarchal. [I saw the film as] a good way to talk about how institutions aren’t really working for their citizens. But it’s not just institutional, it’s society too.

“I am based in the states; my sister disappeared in Sierra Leone, but it’s an everywhere story. Misogyny and racism are global issues. We’re not stopping to see the humanity in people [when] black women or Indigenous women go missing. We don’t see the value in women, especially black women.”

She hopes the film will encourage others to tell their stories, something she is already doing through her non-profit organisation, Kosinima, which offers grants to black film-makers around the world, especially women.

In Babalola’s mind the “giants” of the film’s title were society, misogyny and grief.

“Grief is always going to be there – sometimes I wish I could ask someone to hold it [for me], just for an hour. And sometimes friends do, but it feels there is a limit to that – and grief doesn’t have a limit, so I have to sit with it by myself.”

But when a friend said she thought the giants were her and her mother, she gained a new perspective on her experience.

“It gave me a boost. I think I had always thought, well, of course, we just did what we had to do [in the search for KaiKai]. But we were so determined; we were the giants trying to get through this ordeal.”