Janet Jackson was at Haider Ackermann's show this morning. It's a sure sign that his days as fashion insiders' favorite secret are over. But gone Hollywood he hasn't. The Colombian-born, Belgian-trained designer's vision is as unwavering as ever. It crystallized on his runway today, where the clothes somehow managed to be utterly soigné and fabulously louche at the same time.

Elaborating on one of the ideas from his evocative show at the Palazzo Corsini in Florence during Pitti Uomo in June, Ackermann turned silk pajamas into languid eveningwear—the sash of a silk cami trailing behind the model as she wafted down the runway; a robe spilling off one bare shoulder. That feeling of dishabille extended to gowns in electric blue, red, emerald, yellow, or black, which plunged to the navel in front, or, more daringly, came with curving slits at the pelvis. Other options for evening married tuxedo lapels to a narrow skirt, leaving the entire back bare.

Ackermann didn't neglect daywear, either. Leather vests and jackets blousoned over soft silk pants and a long pleated skirt. And his signature cropped jackets were finished off in back with heart-shaped bows that prompted little gasps of how-does-he-do-that delight from the front row. When the designer came out after the finale, the crowd erupted in ecstatic applause, and he deserved it.