Queen Latifah as “Empress of the Blues” Bessie Smith in HBO’s “Bessie.” (Frank Masi/HBO)

HBO’s “Bessie,” a biopic premiering Saturday that stars Queen Latifah as the blues singer Bessie Smith, is a thoughtful and at times stirring example of how a film can add texture to a legendary figure.

Not very far into “Bessie” comes the recognition that we are watching a true labor of love, meant to celebrate the “Empress of the Blues” and teach something to those of us who might not have done all our homework on the careers and cultural contributions of various blues icons. This care is evident in the performances not only from Latifah and co-star Mo’Nique (as Ma Rainey, Smith’s mentor, rival and close friend) and Khandi Alexander (as Smith’s abusively resentful sister), but all the way down to those playing bit parts and extras.

Therein lies a small problem, too, which is not unique to “Bessie”: Many biopics suffer from a sense of duty, particularly those about the personal travails of 20th-century musicians who worked their way up from poverty to notoriety. “Bessie” also grapples unsuccessfully with breadth, trying admirably to reach both arms around the singer’s entire life in under two hours. At what point is a filmmaker allowed to craft a meaningful, thematic film and at what point must she deliver a dramatized Wikipedia entry?

Instead of focusing on just one period or narrative hook in Smith’s life, director and co-writer Dee Rees is faced with the challenge of cramming it all in — from flashbacks of Smith’s childhood despair to her entry into showbiz with the help of her loyal older brother, Clarence (Tory Kittles). “Bessie” follows its subject’s big career breaks, her bisexuality and her refusal to bow to the racism of the music industry and her feelings about the white and black cultural arbiters who felt it was their job to judge her authenticity.

The film also depicts her first marriage to her manager, Jack Gee (“Boardwalk Empire’s” Michael Kenneth Williams), and her descent into alcoholism, ultimately ending on her comeback in the early 1930s. It’s all here, except, curiously, any mention of Smith’s untimely death in a 1937 car wreck. (She was 43.)

Rees is working from a screenplay originally written by the late Horton Foote in the early 1990s; Latifah was first approached by producers interested in casting her as Smith not long after that. The project languished — almost too long for Latifah, now 45, to still convincingly play Smith as a teenager and young woman just starting out.

But it doesn’t take much time for Latifah to inhabit the role and dispel any doubts; the singing (hers and Mo’Nique’s) is heartfelt and strong, but no match for the source material.

Smith’s rise to fame in the 1920s is an invigorating experience to re-create and watch, but “Bessie” is at its best and most effectively haunting when Smith falls on hard times. There’s something cruel about connecting to the life of a blues singer most fully when she’s down on her luck and sitting naked before a mirror, despondent about certain outcomes. “The blues is not about people knowin’ you,” Ma Rainey tells Bessie early on. “It’s about you knowin’ people.”

As “Bessie” eventually makes clear, the blues is also about knowing yourself.

Bessie

(112 minutes) premieres Saturday at 8 p.m. on HBO, with encores.