Cassandra Wilson started out as a jazz singer, doing gigs with several innovative bands (including Brooklyn’s experimental M-Base collective) and at the same time recording typical jazz-singer let-me-entertain-you stuff—"Night and Day" and “Blue Skies” and shooby dooby dooby. Eventually the Mississippi-born New York–based vocalist, who reigned among the elite jazz singers of the 1980s, became restless, and began to look beyond torch songs for inspiration.

So she looked outside of jazz for inspiration. In interviews, she’s recalled how she began seeking new challenges for her voice, a mighty instrument blessed with husky overtones and an alluringly smoky woodish hue. She began to integrate gospel and blues and pop songs into her performances, eventually assimilating them into music that blurs genre distinctions entirely. Blue Light ‘til Dawn is the first album to capture that shift. It features wondrously spare, molasses-slow versions of Robert Johnson (“Come On in My Kitchen,” “Hellhound on My Trail”), Philly soul (Thom Bell and Linda Creed’s “Children of the Night,”), pop (Van Morrison’s “Tupelo Honey”), and torch song (“You Don’t Know What Love Is”).

Working with a small group of inventive New York jazzers, emphasizing hand drums and percussion over trap set, Wilson cultivates the opposite of dazzle—hers is an inviting, shadow-filled sound that calls from a lonesome bayou. Atmosphere dictates everything that happens on these tracks, and helps knit together pieces from disparate ends of popular music. It also guides Wilson’s vocals: Her sullen “Hellhound” wanders far from typical blues woe, yet winds up an apt, weary summation of it all the same.

Blue Light became an adult contemporary hit, and set Wilson on the course she’s pursued since. The records are all engrossing and shaped by extremely sensitive musicianship, but Blue Light has something more—the renegade energy of one who, having taken a flying leap, is just discovering a new mode of expression.