In the wake of her superb new album Red Dirt Girl, Emmylou Harris commented: "All of a sudden, I'm in a place that I didn't even know existed before." For 30 years, Harris has been a fixture in country music, both in her own right and in partnership with an assortment of greats, from Gram Parsons and Neil Young to Willie Nelson and Johnny Cash, but has never sounded as focused and sure of herself as she does now. It's as if she suddenly has a complete vision of herself as musician and songwriter, and can put her still-evolving career into a new perspective.

Accompanied by her skilful backing trio, Spyboy, Harris built this performance on a platform of songs from the new album, but also found time to reflect on some of her career landmarks. From the Parsons era, she highlighted Love Hurts and reworked Hickory Wind into a slow, mystical reverie. The ghosts of various line-ups of her erstwhile Hot Band flitted through The Boy from Tupelo and a honky-tonkish Wheels. Poncho & Lefty was a tribute to the late Townes van Zandt.

But it was the new material that proved particularly spellbinding. Never a prolific songwriter, Harris has now managed to tap into a grippingly resonant vein of material, as though exorcising decades' worth of dreams, demons and memories - "water from a deeper well", as she sings. It's the kind of purple patch any writer would cheerfully rip off their right arm to attain, and the visionary nature of some of these songs is staggering. Hour of Gold could have been exhumed from the grave of some medieval mystic. Michelangelo resembles a particularly savage soliloquy from Macbeth. The most stunning of the lot was Bang the Drum Slowly, Harris's requiem for her father, a former Air Force pilot. Part hymn and part dirge, it could have been horribly mawkish in lesser hands, but Harris sang it like an out-of-body experience, stunning the audience. As the final chords faded away, she hummed The Last Post.

This is the prime of Miss Emmylou Harris, and we should make the most of it.

&149; Emmylou Harris plays the Royal Concert Hall, Glasgow (0141-353 8000), tomorrow, then tours.