Beyoncé's Life Is But a Dream a curated peek behind the curtain

Fresh from channelling a Sasha Fierce-like persona on the Super Bowl stage, international pop star Beyoncé Knowles is offering a glimpse at a softer, more vulnerable side in her upcoming HBO documentary Life Is But a Dream.

Set to debut Saturday, the nearly 90-minute film purportedly gives "raw, unprecedented access" to the notoriously private performer.

From her early days as the barely veiled central figure of Destiny's Child through her nary-a-hair-out-of-place blockbuster solo career, Beyoncé Knowles has lived a meticulously crafted existence. And so, this self-directed, self-produced peek behind the curtain is more carefully engineered confessional (with some admittedly electrifying performance footage -- we all know the girl can deliver onstage) than a true exposé on Bey.

Beyoncé's doc offers a highly controlled peek into her personal life. (HBO Canada)

Precisely scheduled to debut after her Super Bowl halftime gig and ahead of her new album and world tour, Life Is But a Dream will undoubtedly satisfy Queen B's fan base with its family footage and laptop-video diary entries (in which she appears flawless even sans makeup).

To be fair, the doc does venture into some moments of honesty. Her usually cool-as-a-cucumber rap mogul hubby Jay-Z is shown -- in what appears to be a shaky, cheesy cellphone video (c'mon, we've all made these, right?) -- goofily serenading her with some Coldplay karaoke, for instance.

More potent are Knowles' revelations about a miscarriage during her first pregnancy several years ago. Unknown at the time, but leaked in advance of this doc, her admissions are heartrending and explain her extreme privacy when she became pregnant again (with her new best friend and "homey," daughter Blue Ivy).

Still, from its frustratingly vague treatment of Beyoncé's ousting of her father Mathew Knowles as her longtime manager to the gentle ball-busting scenes showing her admonishing members of her creative team, Life Is But a Dream invokes the aura of that girl who shrewdly claims she's a perfectionist when asked about her weaknesses. It's Bey's latest, scrupulously plotted transition: Sasha Fierce becomes Mrs. Carter (invoking the name of her new tour, naturally).

It's Beyoncé -- and Beyoncé alone -- who's telling this story and it's a tale that will likely leave most viewers still scratching their heads about the real woman behind the wind-blown tresses, bootylicious outfits and roof-raising performances.

Beyoncé: Life Is But a Dream premieres on Saturday at 9 p.m. ET on HBO Canada.