It was Grammys weekend 2012 and the mood in the Beverly Hilton was electric. The swanky Los Angeles hotel was buzzing ahead of the music industry’s biggest awards ceremony and an exclusive party hosted by Clive Davis, the legendary American executive who was the guiding hand behind some of the world’s biggest stars.

Among them had been Whitney Houston, the singer with a once-in-a-generation voice, a perfect vibrato and a range stretching from alto to soprano. By then, of course, despite record sales in excess of 200 million, she was as famous for her descent into drug-addled despair as she was for her worldwide No 1 hits I Will Always Love You and One Moment In Time.

But this, she had told friends, was a big night for her. She was well again, excited about her new music, a new acting role and her return to physical fitness. And she couldn’t wait to show off her metamorphosis at Davis’s hot-ticket party.

A new documentary about the singer Whitney Houston attempts to solve the mystery behind her tragic demise

Houston’s publicist Lynne Volkman recalls what happened next. ‘I was about to get in the shower when I got a call to come to the fourth floor immediately. On my way there I was thinking what was the worst-case scenario? I rushed out of the elevator and said to security, “How is she?” And they replied, “She’s dead.”’

It was around 4pm on February 11, 2012. Inside the now taped-off Suite 434, Houston had been found, alone, floating face down in a bath full of scalding water. Drug paraphernalia littered the room. The cause of death would be given as drowning and the ‘effects of atherosclerotic heart disease and cocaine use’. She was 48 years old.

It was a sordid end and also a mysterious one, leaving a series of unanswered questions. Who had supplied the drugs that killed her? Why had Houston, with apparently so much to live for, taken them? Could someone have saved her?

In fact, the only certainty at the time was that the woman who just a few years previously had starred opposite Kevin Costner in The Bodyguard and thrilled with a string of hits including Saving All My Love For You and The Greatest Love Of All, was gone.

Now, film-maker Kevin Macdonald thinks he’s found some – though not all – of the answers. Whitney, directed by the Oscar-winning Scotsman, is a documentary that explores how a tall, shy, skinny teenager from New Jersey became the greatest pop diva of her day and then threw it all away as drugs ravaged not just her body but her voice too.

Over the course of some 70 interviews with those closest to Houston – including her mother, gospel singer Cissy Houston, and her cousin, Dionne Warwick – Macdonald uncovered a tangle of family secrets. Together they explain how Houston was never given the stability and strength she needed to sustain her career when it went stratospheric.

Whitney, directed by the Oscar-winner Kevin MacDonald, is a documentary that explores how a tall, shy, skinny teenager from New Jersey became the greatest pop diva of her day

Her late father, John, who had become her manager, was skimming her funds. Her brothers Gary and Michael, both of whom were on her payroll, were chronic drug abusers who helped accelerate her own addictions. Her mother had had an affair with the minister of the family church. And, most shocking of all, her cousin had sexually abused her.

Where Macdonald has not succeeded is in explaining her death. It’s not a failing of his work, rather a reflection of the chaotic nature of her passing. ‘I had four different people who I all caught out lying about what had happened at the end of Whitney’s life,’ the director reveals. ‘But I don’t think she was murdered, I have no evidence for that.’

The closest he comes to suggesting foul play is in the testimony of Houston’s assistant Mary Jones, who told him the floor of the bathroom where the star was discovered was sopping wet: ‘Somebody was in the room with her, had given her these drugs, and had found her drowned in the bath, switched off the taps and left the room,’ she says. She cannot, however, identify them.

Whitney with her mother Cissy in 1985. The documentary uncovers a tangle of family secrets

Even if Whitney wasn’t murdered, she was definitely failed. One by one, Macdonald tracks down all the protagonists in the story of Houston’s life and death, and asks how they let her down.

He began with her closest family: her brothers. He reveals: ‘Gary and Michael grew up at the height of the crack and cocaine boom in New York. When Michael was 12 or 13, he was a mule taking drugs across the bridge from New Jersey to Manhattan on his bicycle – because the police wouldn’t stop kids. He’d earn $200 and thought, “Wow, this is the life.” Gary’s first drug experience was aged ten – he was given heroin by his cousin on a park bench. He passed out and his cousin just abandoned him there.’

As Gary confesses in the film: ‘Yeah, we took a lot of drugs every day, s*** that usually kills…’

The boys’ struggles continued into adulthood and they admit to bringing drugs into their sister’s world – and going out to buy drugs for her when she was on tour.

It’s also Gary who – eventually – provides the stunning allegation at the heart of the documentary, revealing to Macdonald that he was sexually abused in childhood. The abuser, he claims, was his cousin Dee Dee Warwick, sister of Dionne. And Dee Dee, he alleges, also abused Whitney.

Whitney with daughter Bobbi Kristina in 2011. The 22-year-old died in 2015, six months after being found unconscious in her bathtub, in an eerie echo of her mother’s demise

‘Most people in the family thought Dee Dee had the best voice, better than Dionne,’ says Macdonald of the singer, who had her own drugs problems and who died in 2008, aged 66. ‘But she never got the break. Dionne got lucky and met Bacharach and David. And Dee Dee was gay. That was known at the time; the family would tell you it wasn’t, but it was.’

A black woman, from a church background, in the Sixties, who was gay – one can only imagine the pressures on Dee Dee. ‘You can only feel a degree of pity for her as well,’ says Macdonald.

Money, along with sexual abuse, also played a key role in tearing the family apart. Bette Sussman, Houston’s long-standing pianist, was by her side in 1995 when the singer’s financial empire began to teeter. ‘We finished up a tour in Hawaii and she fired all these people in her company, and then put family members in place,’ remembers Sussman. ‘From my standpoint, it was crazy: you’re firing all the people who are trying to lead you in the right direction. But Whitney didn’t want to be told what she could and could not do.’

Houston’s musical director, Rickey Minor, explains the consequences of this naive decision. ‘Whitney was carrying all these people – her payroll was a huge responsibility. She basically took care of some 300 people, put their kids through school. She put my son through school, and enabled me to buy a house. That’s a huge responsibility for a corporation, let alone a single woman. If she doesn’t work, no one eats.’

One by one, Macdonald tracks down all the protagonists in the story of Houston’s life and death, and asks how they let her down

The burden of managing her business without proper, impartial advisers saw Houston hire her father John as her manager, only to discover later that he was stealing from her. As Houston’s brother Gary says: ‘She found out about all the money he stole and cut him off.’ John Houston retaliated with a lawsuit demanding £75 million from his daughter. It was thrown out of court, one of the many family catastrophes and betrayals that destroyed her equilibrium.

If the singer of the world’s biggest power ballads thought she might find an emotional shield from her family through love and marriage, she was mistaken. Bobby Brown is the ‘bad boy’ singer to whom she said ‘I do’ in 1992, only to have their marriage dogged by accusations of sexual assault and infidelity. They divorced in 2007.

In front of Macdonald’s cameras, Brown claims, surreally, that drugs had ‘nothing to do with this story’. This despite very public low-points such as an infamous 2002 prime-time interview in which the seemingly intoxicated singer proclaimed that ‘crack is whack’.

The documentary itself also includes troubling home-movie footage of a clearly high couple, patently failing their daughter Bobbi Kristina and setting her on the downward spiral to her own death. (The 22-year-old died in 2015, six months after being found unconscious in her bathtub, in an eerie echo of her mother’s demise.) Yet it does not hold Brown solely responsible.

Minor says: ‘I never saw Bobby verbally or physically abuse [Whitney], but he was a strong personality. And for any man, especially a black man, it’s emasculating to have the woman be the breadwinner, and people calling you Mr Houston rather than Mr Brown.’

Houston looking unwell while travelling in Europe in 2005. Even if Whitney wasn’t murdered, she was definitely failed

Sussman agrees, saying: ‘I don’t blame Whitney’s drug addiction and death on him. I blame her for allowing him to bring her down.’

Dramatic and entertaining, Whitney reminds viewers of the glories of Houston’s voice and the film is a poignant and powerful portrait of an artist who helped define an era. When Whitney premiered in Cannes in May, the Houston family was expected to make a statement about the abuse revelations – but at the time of writing, nothing has appeared.

In the end, all concerned with its making share the hope of Lynne Volkman: that the film will, if not excuse or exonerate the behaviour that killed her, at least go some way to explaining it and help rehabilitate the memory of Whitney Houston.

‘I hope after watching this, people are going to have more empathy toward Whitney,’ says her former publicist, ‘and not think she was this foolish girl who squandered her life. I hope they know there was something going on in her, behind everything, that explains it all.’ 

‘Whitney’ is in cinemas on July 6 

Ten more thrilling documentaries ready for take off this summer 

1. Spitfire 

Featuring aerial footage of Spitfires soaring through the sky, digitally enhanced film from the Forties and first-person testimony from veterans, directors David Fairhead and Ant Palmer reveal how this icon changed the course of history. As Geoffrey Wellum of 92 Squadron eulogises, ‘You can’t fly a Spitfire and forget about it. It stays with you forever.’ Out July 20 

2. The Opera House 

The chronicle of New York’s Metropolitan Opera House from its cramped 1883 beginnings on lower Broadway to the specially built ‘temple to opera’ at the Lincoln Center. A story about how the city’s planners shaped Manhattan as they raced to get the venue finished before the triumphant debut of Antony And Cleopatra in 1966. Out July 1 

As Geoffrey Wellum of 92 Squadron eulogises, ‘You can’t fly a Spitfire and forget about it. It stays with you forever’

Film historian Mark Cousins goes in search of the man behind the film-making genius, Orson Welles

3. Tracking Edith 

With a touch of the film noir, director Peter Stephan Jungk unravels the story of his great aunt, Edith Tudor-Hart, an Austrian-British photographer and KGB agent. Through interviews with family members (some of whom refuse to believe Jungk’s discoveries) and historians, we learn how this vivacious woman, who came to London between the wars, helped recruit the notorious Cambridge Five spy ring that infiltrated Thirties Britain. Out July 27 

4. Pope Francis: A Man of His Word Veteran 

German film-maker Wim Wenders, who once contemplated becoming a priest, captures the current Pope as both rock-star Catholic figurehead preaching to the masses and pensive man alone in his chambers. Lengthy interviews show him wrestling with global issues such as the environment, immigration, economic injustice and the disintegration of the family. Out August 10   

5. The Eyes of Orson Welles 

Film historian Mark Cousins goes in search of the man behind the film-making genius. Rather than chalk off the familiar tale of Citizen Kane and Hollywood exile, Cousins focuses on Welles’ childhood, his politics, his contradictions and his travels. Indeed, following in the director’s footsteps, Cousins often places his camera exactly where Welles once had. Out August 17

The Staircase follows the trial of writer Michael Peterson, whose wife was found dead at the bottom of the stairs in 2001

TV documentaries 

1. The Staircase 

Docu-series following the trial of writer Michael Peterson, whose wife was found dead at the bottom of the stairs in 2001. The story swings to and fro, and even after watching all 13 episodes, armchair detectives will still be debating Peterson’s guilt/innocence. Netflix 

2. Virunga 

Four conservation workers take on rebels, poachers and an oil corporation as they fight to protect Africa’s oldest national park. Netflix 

3. Making A Murderer 

Exonerated after 18 years behind bars for a sex crime he did not commit, Steven Avery is released… only to be accused two years later of murder. Filmed over a decade, this is a masterful account of a Kafka-esque miscarriage of justice. Netflix 

4. The White Helmets 

Oscar-winning film following three volunteer first responders dodging bombs and bullets in war-torn Aleppo, Syria. Shocking, bloody and inspiring. Netflix 

5. Exit Through The Gift Shop 

A French film-maker attempts to track down shadowy street artist Banksy, only to find the guerrilla graffitist turn the camera right back on him. Amazon Prime Video