Stefano Pilati, the man who emerged from the backroom at YSL Rive Gauche, now has the fashion world waiting with bated breath on his every belt and ruffle. For spring, that waist-cinching belt—the fulcrum of his silhouette—came in woven straw, and the ruffles, once applied to peplums and bustles, were trained to burst from shirt bibs and cascade in bands down the front of his narrow skirts. Pilati's opening look was a pair of matador pants, a frilled shirt and a belt—voilà: Spanish. But, as so often this season, you had to check the ultramodern shoes to get the crucial slant: assertively dramatic metallic platforms with triangular heels sculpted into a steep ridge at the back, like the hull of an ocean liner.

The backstory here is that Pilati spent last summer researching Picasso, mulling over Saint Laurent's 1976 Spanish collection, and adding random insights triggered by his preview of the Dada exhibition that opened this week at the Pompidou Centre. "I wanted something more spontaneous and passionate," he said, "with a bit of the industrial." The designer fused all those influences into a confident reiteration of his dressed-up, long-legged, nouveau-French look, drenched in rich color treatments that ran from subtle Cubist shades of beige, ochre, saffron, and black, through to bull's-blood red, purple, and pristine white. Skirts might come cropped above the knee; as long, thigh-clinging pencils; or with a bubbled volume, caught into a narrow flounce; and were balanced with neat, short jackets and a myriad variations on his incredible blouses.

This season, Pilati brought a new lightness to his intense interest in surface detail. He compressed the idea of black mantilla lace into spidery-fine trompe l'oeil embroidery that covered a crisp white pencil skirt, and traced the shoulder and neckline of a sheer organdy blouse. Chiffon pompoms bobbled along the flanks of skirts and the edges of the bride's slim white cape, and even some of the bags caught the aerated mood—little boxes made of filigree metal in a Moorish screen pattern. If there was any remaining doubt about the attraction of Pilati's rigorous look, it was comprehensively countermanded by the gathering of fans who had turned up wearing his extreme platforms—the runaway hit of YSL's fall collection. Judging by the chat in the excited crowd afterward, the lines for his bold Dada-moderne shoes are already forming.