THERE IS A scene - left on the cutting room floor during the edit of Bob Dylan's epic and messy 1978 film Renaldo And Clara but unearthed for Martin Scorsese's Rolling Thunder Revue documentary in 2019 - that perfectly demonstrates the controlled power of Joni Mitchell. Filmed with her guitar at the home of Gordon Lightfoot, in the company of Dylan and Roger McGuinn during a break from the travelling show which Mitchell hopped on and off, she is teaching them the chords to Coyote, set to be the first track on the bewitching Hejira.

Mitchell, in a black beret, begins to play its syncopated acoustic rhythm, and from her opening line - "No regrets, coyote" - her delivery is magnetic, as she pushes and pulls and teases the phrases (detailing her affair with a slyly seductive figure long believed to be play- wright Sam Shepard). Dylan looks either entranced or stunned, or a mixture of the two.

On record, Coyote cast its spell from the moment the needle dropped into the groove, its gently driving force setting Hejira into forward motion in much the same way as All I Want had done on Blue, though at an accelerated clip. Immediately leaving behind notions of folk or rock or jazz, it carved out new terrain: a dreamlike, proto-ambient sound that was unmistakably Mitchell's own. Percussionist Bobbye Hall's congas brought soul into the equation (he'd worked with Marvin Gaye and Bill Withers, among others), while bassist Jaco Pastorius wove in and out, punctuating his insistent groove with bright bursts of harmonic chords. Mitchell mixed her overdubbed acoustic guitar parts with semi-acoustic electrics coated in chorus and phasing, giving the album its swirling, warm-bath effect.

Joni Mitchell had travelled far and wide to reach this pivotal point in her creative development. Hejira - which the Merriam-Webster dictionary defines as "a journey, especially when undertaken to escape from a dangerous or undesirable situation" - is part poetic travelogue, part road movie, detailing Mitchell in effect running away from the bad vibes surrounding the singer's break-up with her drummer John Guerin (who would nonetheless play on four of the album's tracks).

CANCELLING THE REMAINDER of the tour in support of The Hissing Of Summer Lawns in February 1976, she accepted an invitation her wanderlust hit again and, much as it had with the European travels that informed Blue, inspiration struck. Two friends asked the singer to accompany her on a cross-country drive from LA to Maine, before she travelled on solo, driving back to California via a circuitous route that took in Florida and the Gulf of Mexico. Rebelliously driving her white Mercedes with- out a licence, disguising herself with scarves and hats when she ventured into towns, she enjoyed the freedom of travelling alone and incognito.

"I'd do these disappearing acts," she told writer Timothy White. "I'd pass through some seedy town with a pinball arcade, fall in love with people who worked on the machines, people staying alive shoplift- ing, whatever."

At night, in a series of unfancy motel rooms, she wrote songs for Hejira. In the beautiful, mesmerising Amelia - enhanced in the studio by Larry Carlton's slow-moving, high-altitude slide guitar parts passing by like icy cirrus - Mitchell identified with the disappeared "ghost of aviation", Amelia Earhart, who vanished in 1937 as a result of her own epic adventuring. The singer's motel dreaming involved "747s over geometric farms" in a song she saw as being an address "from one solo pilot to another... sort of reflecting on the cost of being a woman and having something you must do".

Elsewhere, the sound pictures painted on Hejira transported the listener directly to its various locations. In Furry Sings The Blues, via Guerin's light touch, late-night drums, and Neil Young's wailing harmonica, we find ourselves in the gnarly and fast- decaying septuagenarian bluesman Furry Lewis's apartment on Beale Street in Memphis where Mitchell visited him. "Bring him smoke and drink and he'll play for you," she advises, before describing how "he points a bony finger at you and says, 'I don't like you.'" (Lewis hated the song and moaned that he'd been cheated out of royalties.)

In the sprawling, 10-verse Song For Sharon, we're there with the singer in New York as she haunts Staten Island and Greenwich Village, suffering inner turmoil expressed in the form of an imaginary letter to her childhood pal Sharon Bell, happily married to a farmer back in Saskatoon, while Mitchell remains unsettled by her own troubled love life. The only song reportedly written while Mitchell was high on cocaine, it feels like a rush of confession that we're all eavesdropping on.

Back on the road, her journey is vividly evoked in the misty watercolour title track as being strangely aimless ("I'm travelling in some vehicle/I'm sitting in some cafe"), before, "porous with travel fever", she offers a sweeping rumination on love and mortality, peaking in the great poet-worthy declaration that humans are "each so deep and superficial/Between the forceps and the stone". Yet, after all of this philosophising, she acknowledges that the lure of love will inevitably pull her back to "the petty wars" of romantic entanglement

BY THE BROODING Black Crow, Coyote in negative, the singer is identifying with the bird in flight, soaring over the highway and then "diving down to pick up on every shiny thing". Here, the romance of the road is beginning to pall, and Mitchell looks into a bathroom mirror, only to see "my haggard face" staring back.

Pining for John Guerin once again in Blue Motel Room, Hejira's mandatory jazz number, she composes a mental missive proposing a deal: he stops his philandering around town, and she'll quit her travels. By the closing track, Refuge Of The Roads, she is slowly winding her way back to California. Stopping at a gas station, she gains vital perspective seeing a photograph on the wall of Earth taken from the moon, noting that "you couldn't see a city... or a forest or a highway... or me here least of all". For all of its rich and strange sonic atmosphere, Hejira was particular welcomed by Joni Mitchell fans for its return to first person confession after the third person narratives of The Hissing Of Summer Lawns.

Still, Hejira - brilliantly original and tough to categorise - was initially perceived as being a difficult album, lacking in easily absorbed melody and only beginning to reveal its mysteries after repeated plays. The album reached US Number 13 (and two places higher in the UK) but was viewed as a commercial slide when compared to its two predecessors making the Billboard Top 5.

Four days after the release of Hejira, on Thanksgiving Day 1976, Mitchell stepped onto the stage at the Winterland Ballroom in San Francisco to make her guest appearance at The Last Waltz, The Band's own farewell to the road. After picking up her Martin acoustic and slipping into Coyote, bassist Rick Danko gazed on admiringly as he played along, and the rest of the group slowly built to a crescendo pulling the song back towards rock. Joni stole the show - it had been a long, strange trip, but her creative freedom now stretched out ahead of her, like a road disappearing over a new horizon.