One evening in late January, Haider Ackermann, the new designer at Tom Ford, was tucked into a velvet banquette at La Reserve, the discreet, tryst-worthy hotel not far from the Élysée Palace in Paris. He was doing his best impression of Tom Ford, the man.

“Hello, Haider,” Mr. Ackermann purred, his voice dropping an octave and taking on a sultry tone. He was acting out a phone call he had received. “It’s Tom.” He paused to take a breath, as if he were tasting the air. “Call me,” he said, making it sound like “come here.”

Then, his voice back to normal, he added, “Of course I did.”

That was about eight months ago. It turned out Mr. Ford, who had sold the company that bears his name to Estée Lauder in 2022, had a proposition for Mr. Ackermann. After only a year, the new owners — Lauder and Ermenegildo Zegna — had decided that Mr. Ford’s immediate successor, Peter Hawkings, was not the right man for the brand.

To replace him, they had only one name on their list, “and that name was me,” Mr. Ackermann said. Though he had recently taken a job as creative director of the outdoor company Canada Goose and was in the midst of negotiations to become the designer of a big French fashion house, Mr. Ackermann started fantasizing about Tom Ford.

“I was immediately thinking about what I should do,” he said. “What I would do.”

Now, after multiple conversations with Mr. Ford, Mr. Ackermann is on the verge of introducing a new Tom Ford collection for men and women. The goal is to do what Mr. Hawkings could not and redefine Tom Ford for the post-Tom Ford era.

Mr. Ackermann has moved the fashion show to Paris from Milan and is in the process of moving the company headquarters from London. He has teased his new look on his friend Timothée Chalamet, who wore custom Tom Ford by Haider Ackermann on the red carpet at the Golden Globes in January: a skinny, rhinestone-speckled black suit with a sky blue polka-dot silk scarf slung around his neck. But he is still trying to find “the thread between what I call sensuality and what Mr. Ford called sexuality,” he said.

“The exercise is more difficult than I thought it would be,” Mr. Ackermann said, noting that he had not made a knee-length pencil skirt, a Tom Ford signature, in his entire career. But, he went on, “the man, the woman, they are not strangers to me. I know we will get together, but it takes time.”

Especially because it turns out this particular relationship is kind of a throuple.

The Ghost in the Machine

“The complexity of this story is that the house of Tom Ford is Mr. Ford,” Mr. Ackermann said. “There’s no other ambassador than Mr. Ford.” Tom Ford is his ghost in the machine.

Plenty of designers have taken over houses that still bear the names of the designers who founded them: Dior, Chanel, Givenchy, Gucci, Saint Laurent — these were all real people. That’s where the idea of brand “DNA” originates.

But at a certain point, a brand can become so divorced from its founder that the name is just an abstraction. Once enough other designers have inherited the title, it’s hard to remember that clients were once loyal to a specific silhouette or design. That opens up the possibility for new creative directors to make the house their own.

A house like Tom Ford is somewhat different. That’s because it’s only 20 years old, and, whatever his official status, Mr. Ford still seems very much around.

Founded by Mr. Ford and his business partner, Domenico De Sole, in 2005, Tom Ford-the-brand was a kind of test case: Would Mr. Ford, who had become a celebrity by remaking Gucci and creating Gucci Group (the seed of the conglomerate that eventually became Kering) before leaving in 2004 to make movies, have enough name recognition to build a label from scratch on the mere power of his stubbly, unbuttoned-shirt appeal?

The partners started by licensing fragrance (to Lauder), then eyewear and then expanded into men’s wear (with Zegna) and women’s wear. But while the beauty line became a smash hit, and the suiting did fine, the women’s line always seemed more of a red-carpet indulgence than an actual business.

Nevertheless, just over two years ago, after Mr. Ford’s husband died and he decided to focus on filmmaking (again), Estée Lauder paid $2.8 billion to buy the house, enlisting Zegna to handle the fashion side. Mr. Hawkings, who had worked with Mr. Ford for 25 years, was named designer. He was, Mr. Ford said in an Instagram post, “the perfect creative director.”

It did not take long, however, before rumor had it that Mr. Ford was not happy with comments Mr. Hawkings had made that seemed critical. The reception of Mr. Hawkings’s first collections was mixed, and Mr. Ford, in what seemed like a very public repudiation, wore Saint Laurent to last year’s Met Gala. By July, Mr. Hawkings was out. Soon after, Mr. Ford was on the phone with Mr. Ackermann.

“Mr. Ford and I, we had always been flirting with each other professionally,” Mr. Ackermann said. When Mr. Ackermann was fired from a previous job as creative director of Berluti in a designer reshuffle, Mr. Ford “wrote me such a beautiful letter,” Mr. Ackermann said. “Karl Lagerfeld was the first, and he was the second. It was so moving.”

Haider and the Big Ts

Mr. Ackermann, 52, is something of a fashion designer’s designer. A Colombian orphan who was adopted by a French couple, he spent his childhood moving around the world with his cartographer father before his parents settled in the Netherlands. He attended the Academy of Fine Arts in Antwerp but was kicked out before graduation. (If he did not feel he had anything to say to a teacher, he said, he just did not go to class.) He started his own namesake label in 2003.

His work was characterized by an extraordinary facility with color and decadent romance; he calls his aesthetic “bohemian dreamer.” At one point, Mr. Lagerfeld was enchanted enough to suggest that Mr. Ackermann succeed him at Chanel.

He spent two years at Berluti, but after a dispute with his backer, he lost control of his label and name. Though he has since regained ownership of that name, he was off the runway for a time, save for a much lauded one-off stint as a guest designer for Jean Paul Gaultier couture and the occasional custom order from his famous friends, Mr. Chalamet (whom he has been dressing since 2017) and Tilda Swinton. He calls them “the big Ts.”

As Ms. Swinton tells it, they met in 2004. He sent her a gown for the Cannes Film Festival, but he did not show up for the fittings because he had promised his partner at the time a trip to India. Later, he said, she called and invited him for a patisserie and asked him why he had not been there, and they bonded over the idea of putting relationships over business. She has worn his designs ever since, and they speak, she said, “several times a week.”

“He’s a proper romantic and proper punk, which is the best combination,” Ms. Swinton said, describing his work as “ancient and supersonic at the same time.”

Daphne Guinness, the artist and collector, said Mr. Ackermann was “a Saint Laurent for the space age.” At this point, she calculated that she had about 40 Ackermann pieces in her wardrobe, including the first four looks of his Gaultier couture collection.

During his time away from the runway, Mr. Ackermann did a collaboration with Fila. Then Canada Goose got in touch. “It was very interesting,” he said, going from “being this very niche designer to talking to thousands of people. I had never worn a parka before. Now, I love it. But somebody told me recently that it made my legs look very short.”

Mr. Ackermann has been converted to the joys of camping instead of clubbing. He is a famously good dancer — “incredible,” Ms. Swinton said — and his favorite haunt used to be a club in Rotterdam where, he said, “I was the only boy who didn’t have a shaved hair.” His last summer vacation, however, was spent in a tent in British Columbia. It’s good for perspective.

That’s when he realized that the “massive failure” of losing his own brand “brought me to today, where I understand what I do and why I’m doing it.”

Serving the House

It also brought him to Tom Ford. Gildo Zegna, the chief executive of the Ermenegildo Zegna Group (which also owns Zegna and Thom Browne), described meeting Mr. Ackermann in Paris. “We clicked,” Mr. Zegna said. “We had two long days together, walking around, sitting in the garden, and the social part, the friendly part, was as important as the business part.”

Well, that and the fact that, Mr. Zegna said, “he had the support of Tom Ford, which was very important.”

Which raises the question of what Mr. Ford was doing pulling the strings of a brand he supposedly had nothing to do with. Though Mr. De Sole is on the board of Zegna, Mr. Ford has had no official role in the company since the sale. He declined to comment for this piece, and Mr. Zegna was quick to de-emphasize his role, even as he acknowledged that Mr. Ackermann was Mr. Ford’s idea. But it further raises the stakes for Mr. Ackermann.

“The moment that you work for a house, you have to know your place,” Mr. Ackermann said. “It’s not about you. It’s about you at the service of the house.”

“I didn’t think it was going to be easy to take the role, knowing that somebody has been kicked out in a violent way,” he continued, referring to the departure of Mr. Hawkings. “I’ve been through it. I know what rejection can feel like.”

He is very careful to use the honorific “Mr.” when he speaks of Mr. Ford. (He calls him Tom when they meet in person, he said.) Even as he added: “If people are expecting hot sex, no, you will not see it from me. I don’t have that talent, to be very provocative or very avant-garde. I have different codes. I’m not there to continue exactly the past.”

No More Hot Sex

“We had an appointment in London for lunch one time,” Mr. Ackermann said, describing a meeting with Mr. Ford when they were in the wooing stages. “I arrived earlier, and when he entered the restaurant, he didn’t see me standing in the corner, so I could just observe him. The way he entered the room — the security, the audacity he had in his posture — everyone in the room was looking. It intrigued me. Perhaps, coming from a very Catholic background, I could not be this person. But perhaps, somewhere deep inside, I would like to be this person. To have that kind of freedom.”

That, Mr. Ackermann said, is what his Tom Ford man represents. As for the woman: “I don’t believe in big words like glamour and power. The power of women is not big shoulders. The power of women is what she’s got inside her, the fragility that she eventually wants to show.”

It was two weeks before the Paris show, and he was sitting in his atelier with a vase of white calla lilies behind him. “They are a little more pure than Black Orchid,” he said, referring to one of Mr. Ford’s signature perfumes. “But I think still poisonous and dangerous.” He had decided that his connection to the brand was more about his own memories than any specific silhouette.

“Like in 2012, I went to the Met Gala,” he said. “I was really nervous. I was like, ‘Oh my God, what am I going to wear?’ I’m too shy. But Anna Wintour said: ‘You’ve got no choice. You have to come.’”

So Mr. Ackermann went to a Tom Ford shop and bought a black suit with black dots. And when he was on the Met red carpet, he bumped into Mr. Ford. “He looked at me and said, ‘Oh, you look so smart,’” Mr. Ackermann said. “I was so happy. Then I realized he was not looking at me. He was looking at his suit. So obviously, you will see black dots in the show.”

There will also be knee-length skirts, though Mr. Ackermann was still “trying to find the right line that doesn’t feel too vulgar or too much secretary. I’m challenging myself for sure.”

Mr. Zegna said he believed growth would come for women’s wear, accessories and the European business. Because of the Hawkings issue, the owners are a year behind in their strategic plan. The turnaround has to happen “fast,” he said. “We have not invested to not get returns.”

That’s partly why Mr. Ackermann moved the show to Paris: to signal an ambition to compete at the highest level. Also, he said, “I don’t think Mr. Ford had the easiest time in Paris,” a reference to the period when Mr. Ford appointed himself head of Saint Laurent, to the public criticism of Pierre Bergé and Yves Saint Laurent.

“For me, it was a way to say thank you for trusting me, giving me the honor to continue your story,” Mr. Ackermann said. “I want the world to look at Tom Ford in Paris. The name deserves it, and you deserve it.”

Only 200 people are invited to the show, including Mr. Ford and Mr. De Sole. “I wanted to have something intimate,” Mr. Ackermann said. “I believe that’s what luxury is. It shouldn’t be accessible to everything and everyone. I think the world needs less of a circus. I want it to feel rich, and I want it to feel noble, but I also want it to be quiet. To command attention without screaming.”

Mr. Ackermann has scattered the collection with Easter eggs for Mr. Ford — “things,” he said, “where he will be the only one to see it.”

“If it goes wrong, it goes wrong,” he continued. “But I have no fear. If, after the 5th of March at 7:30, Mr. Ford can say, ‘I made the right choice,’ if I make Mr. Zegna and Mr. Lauder proud, then, OK. Let’s go for it. I’m going to a secret place with the team members and my friends, and we’re going to dance the hell out of it.”