Marc Jacobs finally realized one designer can't do everything. So as he poured more of his energies into his namesake label, he handed off design duties for his more youthful Marc by Marc line to two fortysomething Brits: Katie Hillier and Luella Bartley.

It sure has paid off.

The duo won raves for their initial Marc by Marc fall collection that's in stores now. And in their second collaboration for the brand, now dubbed MBMJ, the British duo has recaptured the spirit that made the collection so appealing to Jacobs' core teens and twentysomething audience in the first place. They've also injected the line with a much-needed dose of enthusiasm.

The spring 2015 collection, which debuted at New York Fashion Week amid a sound and laser light extravaganza that emulated a '90s rave, has a fresh attitude. Bartley — who was a fashion darling when she showed her own collection in New York over several seasons before shuttering the line in 2008 — and Hillier clearly don't take themselves or their clothes too seriously. They believe, particularly for the brand's young customer, dressing up should be fun.

They update fetish gear in a playful way, with latex fabrics in black polka dots over pastel blue and yellow — wildly exaggerated at times in caplets, folded pencil skirts and dresses with excess fabric gathered at the waist. Rubberized boots and molded handbags, also in Jetson colors, have an impish cartoon quality.

Colorful satin dresses, three-quarter pants and blouses in pink, yellow and blue also have a sunny, subversive spirit, along with oversized ninja pants, T-shirts emblazoned with the words "New World System" and cropped hoodie shirts.

Military-influenced looks — a trend for next spring among designers who aim at a young audience, like Rag & Bone and Band of Outsiders — are a bit more serious but offer a unique take. Rather that utilize army green, the designers create crisp flight suits and jackets in white canvas.

A series of "patched" dresses that look like nothing I've ever seen closed out the show. They mix pleats and prints, sweatshirt fabric and bubble wrap in ways that are truly innovative if not terribly practical.

At the end, when the two designers came out for their runway bow, Jacobs, who was seated as a spectator, enveloped them in a joyous group hug.