Shoppers looking for clothing by Emanuel Ungaro in any major American department store are out of luck. Stores have stopped carrying the high-end French line. And here, at the sole Ungaro store, downstairs from the label's offices on Avenue Montaigne, several of the shelves are bare.

Now, Emanuel Ungaro is trying to climb back from one of fashion's biggest debacles in recent years. Two years ago, a collection remembered for its sequined, heart-shaped pasties made Ungaro the laughingstock of Paris Fashion Week. The juvenile designs were a far cry from the sultry gowns made by the founder in earlier decades. The collection had been designed in part by Hollywood wild child Lindsay Lohan.

Add to that the five other designers who have left since founder Emanuel Ungaro retired from ready-to-wear 10 years ago. Ungaro cut ties with the latest, Giles Deacon, earlier this month. The turmoil has muddied the brand's image.

Now, Ungaro (pronounced: OON-ga-ro) is starting over—and it's doing so deliberately without a head designer. When the house shows its spring 2012 collection Monday in Paris, it will be a team effort. Emanuel Ungaro SA's new chief executive hasn't figured out who will take the runway bow.

"I don't believe in overnight sensations," says Jeffry Aronsson, an American who took over in June after heading brands such as Oscar de la Renta, Marc Jacobs International and Donna Karan. "My goal is to revitalize the company in a sustainable way, not a flash in the pan."

Mr. Aronsson believes the brand should stand out in tops and loungewear such as caftans, capitalizing on roots in silks and prints. The upcoming collection has a geological inspiration. A board where designers pinned up images that inspire them showed pictures of eroded rocks. A print used in a sequined maxi-dress and other items was created from images of volcanoes, said Ms. Labib-Lamour. The shapes include peplum tops over long pleated skirts and draping on a red leather dress to form a cowl neck.

Plenty of brands seek new designers when they attempt a turnaround. Gianfranco Ferré has had a revolving door of designers since its founder died in 2007. The Italian label rushed to bring in two freelance talents for its Milan fashion show this week. American fashion house Halston has also had its share of creative chiefs, including Rochas's Marco Zanini and actress Sarah Jessica Parker.

But few designer brands flourish without a public mastermind. Christian Dior is biding its time with studio-designed collections while it searches for a designer to replace John Galliano. Its couture show in July—a mishmash of various decades, with some designs topped off with clown hats—showed what can go wrong without a driving vision.

Max Mara and Hugo Boss are two labels that thrive with no designer in the spotlight. Yet neither boast the high prices of designer ready-to-wear and the image that justifies them.

Ungaro's Mr. Aronsson thinks the in-house talent can mine Ungaro's heritage—bright colors, silk prints and sexy draped dresses—better than a high-profile designer from outside.

"At this point it would be worse for the brand to recruit a known designer because it would be one more direction and message," says fashion consultant Robert Burke.

Less than a week before the fashion show, in a cluttered room, seamstresses were hunched over a long table sewing sequins on lace and cutting red, blue and turquoise fabric for a pair of pants.

Jeanne Labib-Lamour, a designer who previously worked at Balenciaga and Giambattista Valli, called models in one by one to audition for the runway. Ana de Ribeiro, the director of product development, played with metallicized white lace on a mannequin, trying to figure out the right draping.

When it came to deciding what looks would go down the runway, three women—Ms. Labib-Lamour, Ms. de Ribeiro, and the head of marketing, Isabelle Konikoff—sat around a table to watch models try on the dresses. Mr. Aronsson also had his word to say, keeping the women focused on the brand's roots.

Mr. Aronsson says that when he arrived in June, he found a discouraged team of 35 employees. But he noticed young talents, as well as veterans who had worked under the founder. Seeing them and their knowledge of the archives convinced him to rely on them as designers. "I'm not looking for a big name from the outside because I don't want the development of the brand to be dependent on a big ego," he says.

The brand has been traumatized by more than a decade of upheaval. Mr. Ungaro, who is French with Italian roots, sold the house to Salvatore Ferragamo SFER.MI -0.18% in the 1990s. Ferragamo flipped it to Silicon Valley entrepreneur Asim Abdullah in 2005. Over that time, sales collapsed from a few hundred million dollars a year at its peak in the 1990s to $6 million last year, according to documents the company filed with France's commercial court. Ungaro lost $8.5 million last year, according to the documents. Ungaro has retail sales of several tens of millions of dollars, most of which is generated through licenses for products such as perfumes and home linens.

The design turmoil set in after Mr. Ungaro's retirement from his ready-to-wear line in 2001. (The company ended its couture line in 2004 when Mr. Ungaro fully retired.) Giambattista Valli, his deputy, took over the main clothing line. Three years later, Mr. Valli left to start his own line and was succeeded by a string of designers over the next several years.

When sales didn't spike, the company's then-CEO, Mounir Moufarrige, tried a bigger stunt: hiring Ms. Lohan. (He brought in professional designer Estrella Archs to help the actress.) Ms. Lohan's reign lasted one season.

"I'm still convinced it needs a similar sort of cocktail as what I concocted with Lindsay Lohan because it needs buzz," says Mr. Moufarrige, who left the company at the end of 2009, about the same time as Ms. Lohan. "Making beautiful clothes is not enough."

Mr. Deacon, a British designer, joined last year with a four-year contract. But his aggressive aesthetic was a mismatch for Ungaro. His last runway collection was in dominatrix black, far from Ungaro's iconic pinks. He left earlier this month.

Upon his arrival, Mr. Aronsson set out guidelines on what Ungaro stands for, using words such as seductive, sophisticated and intellectually attractive. "Emanuel Ungaro was inspired by the concept of the mistress, but for me it just means a woman who has it all," says Mr. Aronsson.

He says it could take a few seasons before retailers have confidence in Ungaro. The runway show is a step in that direction. "I want the retailers to see this, that it's a whole new page," he says.