Thom Yorke has undergone a subtle transformation in the past decade. Instead of working hard to contort his ego enough to fill arenas, the 50-year-old Radiohead frontman often lets the occasion rise to him. He teases and showboats, riding out mistakes with ponytailed charm. A brave observer might suggest these changes bear the hallmarks of contentment. But, on the occasion of Yorke’s plunge into contemporary classical last night, his laidback rebirth meant little. Despite a delirious reception to his compositions, Yorke appeared stricken before the Philharmonie de Paris crowd. More than his bandmate and sometime guru Jonny Greenwood, now a celebrated composer in his own right, he resembled a Thom Yorke of another era: the vacant ghost who drifted through Radiohead’s 1998 tour doc Meeting People Is Easy.

Yorke debuted two new compositions: the 20-minute “Don’t Fear the Light” and the more songlike “Gawpers.” Performing with him was the Minimalist Dream House band, named to honor the midcentury pioneer La Monte Young. The group comprises the National’s Bryce Dessner, composer-guitarist David Chalmin, and, center stage at enormous Steinways, the electrifying pianists Katia and Marielle Labèque. With her glitter patches and sparkly-striped trousers, Katia looked like a haunted Victorian cowboy.

To start, the Minimalist Dream House band played a suite of old and new compositions. Bryce Dessner’s “Haven,” which premiered at the concert, screamed Bryce Dessner: jumpy and shrill, perilously reminiscent of John Adams, with guitars that jittered up and down arpeggios, and pianos that promised redemption. Its grand, naive sense of wonder and organized chaos perfectly suited the multicolor auditorium, where balconies squiggle around and curve upwards, lifting your gaze to boomerang-shaped panels suspended like aeroplane parts after a mid-air crash.

Yorke made his first appearance of the night a surprise. In a haze of ambient noise shards, he entered midway into Chalmin’s “Particule nº 5—Particule nº 6” wearing a casual T-shirt and blazer. Nobody breathed a word. Chalmin sang, “There must be a place where it all makes sense” as Yorke cooed in angelic counterpoint to the Labèques’ sinister swoops and trills. It took a moment to place a strange tenor in his voice, because it was the tenor of a normal backing singer. Gone was the meek, wavering angst. Instead, a clear and even falsetto. It was impressive but unnerving, like seeing your scruffy friend show up at a wedding in a tailored suit.

Act two began, and Yorke remained absent. His first composition, “Don’t Fear the Light,” was a three-part suite helmed by the Labèques. Its opening minutes, full of creeping keys and ambient gusts, failed to live up to the moment, treading too closely to the spookier tracks from his score for last year’s Suspiria remake. Then something crystallized. At first it sounded clunky, like a witchy cat sauntering across a piano. One key hammered ominously. Out of nowhere, a minor flourish scuttled free and disappeared in a dark flurry. The cat resumed its manic prowl, occasionally touching on a scatty motif I had internalized without realizing it.

For five, 10 minutes, the piece pivoted between contemporary American serialism and European gothic, then staggered back to Russian anarchy. In diabolical moments, Katia sprung back as if a spirit had lurched from the piano and thumped her hard in the shoulder. The sisters played with monstrous energy, like anxious lovers gearing up for a quarrel. There was a strange symmetry where they finished each other’s sentences—and then, with no discernible change, became engaged in different conversations altogether. It was as if one piano was the dream and the other was reality, and Yorke’s score was abruptly shaking you awake.