When it comes to crimes of fashion, constructing an ensemble that would land its wearer on the worst-dressed list is more heinous than ripping off another designer—or so was the moral of this week’s Project Runway. When the episode began, the eager 11 learned they would be designing for socialite Nicky Hilton (reportedly, Ivanka Trump was Bravo’s first choice, but The Donald’s daughter politely declined). With a few red-carpet pics of the heiress for reference, the contestants had an hour to sketch and shop, then returned to the workroom, where tempers flared. Zulema and Marla staged tantrums over their “stolen” mannequins, while Daniel V. struggled to find a fix for his blunder of buying chocolate stretch satin instead of the intended black.

The next day, Hilton hosted a sartorial soiree, complete with Zoolander-style walk-off, at which the contestants presented their creations and themselves. The more subdued of the Hilton sisters, whose own label is called Chick, was consistently gracious, but gravitated most toward Santino, who worked her like a charm. As the party raged on (especially for the newly named "Dirty Diana"), Hilton spotted Marla’s "creation"—a blatant knockoff of the Chloé dress she'd worn in a photo the contestants had received. Did Marla really think the similarity of such a distinctive design would go unnoticed?

On the runway, Nick’s beautifully draped aqua goddess gown and Daniel V.’s formfitting fuchsia-print dress were both standouts. But ultimately, Hilton chose Santino’s periwinkle braided-bodice frock (shown), predicting (oblivious to the previous week's meltdown) that the designer would “go far in this business.” Other strong showings included Kara’s elegant black halter and Emmett’s sparkly-chic babydoll, while Diana’s entry was more uneven: The rhinestone-buckle belt, Hilton agreed, was stylish, but the judges feared the voluminous bottom might spark speculation that Hilton suddenly had too much junk in the trunk. Far worse, Zulema’s two-toned ruched creation was not only poorly made, but also at odds with the socialite’s style. (Can you envision Hilton—not Paris, of course—strolling the red carpet in a Harley-esque leather bustier dress?) Even more mystifying was Guadalupe’s ensemble with pink arm warmer and detachable organza blossoms—a gimmick the judges deemed fodder for Mr. Blackwell and thus even more elimination-worthy than Marla’s copycat Chloé. —Jennifer Ciotta