‘There’s several times the devil tried to get me; but he never gets me…” Since her death in a Beverly Hills bathtub in 2012, the singer Whitney Houston has been the subject of a slew of articles, books, TV shows and (more recently) films, poring over the details of her spectacular rise and fall. Last year, Nick Broomfield’s unauthorised yet surprisingly sympathetic film Whitney: Can I Be Me used revealing backstage footage from a 90s tour to paint a portrait of an exhausted performer torn between identities – sexual, racial and commercial.

Now, Kevin Macdonald, whose impressive directorial CV includes Touching the Void and Marley, enters the fray with an authorised documentary, produced with the assistance of the Houston family and estate, unlocking a wealth of interviews and archive material. Having not previously been a fan of Houston’s music, Macdonald says he was initially reluctant to take on the project, until the singer’s longstanding agent, Nicole David, told him: “I don’t understand why she ended the way she ended. I want you to make a documentary to help me find out.” Through a mixture of vox-pop psychoanalysis and assiduous research, Macdonald duly plays celluloid detective, attempting to “solve” the mystery that forms the backbone of this film. Against the odds, he finds what looks like a smoking gun – a late-in-the-day revelation that has been the subject of much press interest since Whitney premiered at Cannes in May.

While Broomfield traced Houston’s unhappiness to a broad range of identity crises (despite a streetwise upbringing, she was marketed as a bland pop princess, prompting “devastating” boos at the Soul Train awards in 1989), Macdonald latches on to a passing comment from an old interview the singer gave to British DJ Simon Bates. When asked what made her angry, she replied: “Child abuse”, prompting Macdonald to ask Whitney’s brothers if they knew what she might have meant. The trail leads to a female cousin (now deceased), whose predations are placed at the heart of an ongoing family trauma.

By jarringly intercutting news footage with deconstructed images (visual and aural) of a supposedly poptastic life, Macdonald creates a vivid collage that juxtaposes public and personal spheres. Meanwhile, an impressive array of friends, relatives and colleagues recall her triumphs and travails, often with their own agendas. Some are less than forthcoming. Whitney’s famously tough mother, the gospel and soul singer Cissy Houston, only opens up in the church where her daughter (nicknamed “Nippy”) first learned to sing. Ex-husband Bobby Brown refuses to confront or even acknowledge the fact that drugs played a role in their tumultuous marriage. As for Robyn Crawford, Houston’s closest confidante once again declines to discuss their relationship, which seems to have been supportive, sincere and, sometimes, sexual.

As with Asif Kapadia’s Oscar-winning Amy, it’s impossible to watch Whitney without a queasy sense of voyeuristic guilt, particularly when confronted with gleeful media stories about her imploding life, and comedy shows turning her tragedy into the butt of mean-spirited jokes. In truth, there’s nothing entertaining about watching someone’s life unravel, whether or not they are a public figure. But what keeps both Kapadia’s and Macdonald’s documentaries afloat is the reminder of the talent that was there before tragedy struck.

My favourite sequence in Whitney is a description of her Super Bowl rendition of The Star-Spangled Banner in 1991, which engagingly explains the significance of the change from traditional 3/4 waltz-step to the 4/4 time-signature in which Houston performed the anthem. Taking a lead from Marvin Gaye’s soulful rendition at the 1983 NBA All-Star game, Houston found space between the notes to turn a battle hymn into a freedom song, with still spine-tingling results. As with the playful description of the skip-beat difference between ska and reggae in Marley, Macdonald’s film nails a simple musical motif upon which hangs a significant cultural shift.

There are other breathtaking musical moments (some frustratingly fragmentary) in which Houston’s extraordinary voice cuts through the increasing calamity of her private life. In the end, whether or not you think that Macdonald has “solved” the question of her self-destruction, that voice remains as mysterious as ever – ineffable and unforgettable.