Levi David Addai on Hollywood child abuse drama Dark Money: the BBC "saw how urgent this is"

• Meet the cast of BBC drama Dark Money
• When is Dark Money on TV? What's it about? Who's in the cast?
• Damilola, Our Loved Boy review: A moving and harrowing story of loss and redemption

You might think that Levi, the writer behind the Bafta-winning factual TV drama Damilola, Our Loved Boy, had taken his inspiration from listening to the car radio or scrolling through Twitter, absorbing stories about Harvey Weinstein and #MeToo. But you would be wrong – because that particular bomb had yet to explode.

"When I was writing, which was when this first began, this wasn't in the news," Levi tells RadioTimes.com. He'd already come up with the concept and invented the Mensah family, "so I was just happily developing and focusing on this family emerging.

"And then, during – probably just before – we got the green light, that's when all the stuff in Hollywood hit. And was big breaking news. And it was like, oh wow."

In Dark Money, we meet Isaac Mensah (Max Fincham), a 13-year-old Londoner from a working-class family who has been chosen for the star role in a Hollywood movie. His parents Manny (Babou Ceesay) and Sam (Jill Halfpenny) are bursting with pride as he returns from shooting the movie in America. But, when he arrives home, Isaac reveals that something terrible has happened: he was sexually abused by big-name film producer Jotham Starr (John Schwab), and he has secret footage to prove it.

Manny and Sam Mensah take the decision to accept a substantial payout in return for signing a non-disclosure agreement (NDA) and destroying the video. But over the course of four episodes we see the consequences of that decision on Isaac – and on the family as a whole.

Levi is keen to stress this is not "a response piece" and is not "trying to replicate what's happened", instead telling a fictional story about this family.

But while the specific allegations against Harvey Weinstein did not inspire this drama (or the character of Jotham Starr), Levi was already aware of what was bubbling under the surface before all those allegations went public.

"In terms of industry goings-on, I mean that's nothing new. Coming from theatre to TV, you always kind of hear things, and even today – when historic cases come through, it's kind of like, they're known things," he says, adding: "Finally these things come to the surface, and they're in the mainstream."

And the BBC didn't need much convincing about Dark Money, even before the Weinstein story broke.

After the success of Damilola, "they were open to my next idea," Levi says. "And it just so happened that I had Dark Money [and could] say, 'hey I've got this idea, I've got this family, and here's what happens to them.' And they was like, great, let's go for it."

He adds: "I guess that they also saw how urgent this piece is, actually."

This particular family's journey was, in part, inspired by what Levi saw from his car window on Saturday mornings outside his daughter's drama school. "During that time I was kind of observing the other parents that was taking their children to this place," he says.

"It was really interesting just observing the parents who were kind of offering up their children, and absorbing all the hopes and dreams of what the course leaders and the academy leaders was kind of selling, really. 'Ah your child, we can get them an audition for the West End, and film roles, and auditions for soaps and this and that.'"

The parents, he remembers, were "just so trusting" – as are Sam and Manny Mensah in the drama, who send their son Isaac off to America in the company of chaperone Cheryl (Rebecca Front). They have stars in their eyes and big dreams for Isaac's future as a movie star, and so they are completely unprepared for what happens next.

Getting such a serious and sensitive subject right is a big responsibility – which is why Levi met with the Tavistock, an NHS mental health trust which treats children. "I spoke to two child psychologists and they just laid out the raw details of their job and what they have to do," he says. "They really are the front line when it comes to child abuse, and stepping in when they can to try and help and rescue sometimes children from so much horrors that we don't hear about every day. I came out of there thinking they are really the true heroes when it comes to these things. Story after story after story after story.

"I shared as well what I was trying to do and they gave me some really useful advice and encouragement, because they were really pleased about the angle I was trying to come at it."

That advice was incorporated in subtle ways and in "those little details" – including Isaac's body language after the abuse, and the way he reacts to everything taking place around him.

The screenwriter also put a great deal of thought into how to handle the details of the abuse itself – and the decision about what exactly to show on screen.

Ultimately, what we see is the beginning of a video filmed on Isaac's smartphone; the camera is turned to the ceiling, but from the audio we hear a scared little boy pleading with an older man to leave him alone. For viewers at home, this is as far as we ever see or hear – though Isaac's parents Manny and Sam force themselves to watch the video to the end, and they are the ones who later have to verbally describe what Jotham did to their son.

"That was one of the hardest things to actually write," Levi says. "Because – I mean – I think physically I was writing it at arm's length as well, trying to script through it, and I remember going through the process, drafting, and having a discussion with the producer where we were having to have frank discussions, like, literally what has happened to Isaac? What did Jotham do?"

Having Isaac record the encounter on his smartphone was true to the character ("he just wanted to have evidence because being a child, sometimes you think that if you go and tell an adult something they won't believe you") but it was also a way to tell the story without being "gratuitous".

Still, even now as he looks back on writing that scene, Levi says: "I was uncomfortable with it, I hated it. Even now thinking about it I still shudder, because it's like, 'I don't like it.' But then we had to go into that, in reality – what happened, and then from there work out what we wanted to show or not show. But I was really clear that less is best here, and less will be more as well. Because something like this as well you want to tackle very sensitively, and it's not about shock, do you know what I mean? It's about the reality."

Handling the matter sensitively becomes even more important when you're working with child actors, most notably the boy playing Isaac Mensah – a young teenager called Max Fincham, whose other credits include Pokémon Detective Pikachu and The Aliensist.

Director Lewis Arnold brought in a specialist child acting coach, Ben Perkins, to "help them with these difficult subjects," Levi says. But from the start, he noticed the kids were "aware of these things" after growing up with the internet, and a stream of unfiltered news about the world around them.

"It wasn't like they had to really be taken through the basics of, 'this is life, there are bad people and abuse happens'," he says. "They saw what it was, and knew it was wrong. And they wanted to do the best they could within that to portray their characters the best they could, and so they were just really mature and fantastic... I don't want to say it didn't faze them, but they weren't intimidated by this at all."

Dark Money was also a chance to reunite with Babou Ceesay, who had given a Bafta-nominated performance in his previous drama Damilola, Our Loved Boy.

How was it to work together again?

"Oh terrible! Absolute hell," Levi jokes. "No, I love Babou, I've got a real soft spot for him." And though he auditioned other actors for the role of Manny, it was Babou who he kept coming back to.

"When I was developing in my car, I guess maybe because it was so close after Damilola, he was stored in my mind," he explains, looking back on that moment when the idea first began to grow. "We saw a few other people who were actually brilliant, but I just couldn't shake Babou off."

Dark Money begins on Monday 8th July at 9pm on BBC1