Tilda Swinton is one of Hollywood’s most chameleonic actresses: She has played wicked queens, frumpy housewives and David Bowie. So when rumours spread that in the new film Suspiria, the 57-year-old Swinton was secretly cast as an 82-year-old male psychoanalyst, it seemed both outlandish and perfectly believable.

The movie, a remake of Dario Argento’s 1977 horror classic that is due October 26, stars Dakota Johnson as a young dancer who enrolls at an all-female Berlin dance academy only to find out that it is run by a coven of witches. The troupe’s artistic director, Madame Blanc, is played by an unadorned Swinton, but internet sleuths have also pegged Swinton as playing Dr Josef Klemperer, the film’s third lead, under mounds of makeup.

Still, Swinton and director Luca Guadagnino have remained coy on the issue. “Fake news,” Guadagnino said in February, insisting that he had cast a first-time actor, Lutz Ebersdorf, as Klemperer. But when Suspiria had its premiere at the Venice Film Festival last month, Ebersdorf was not among the stars in attendance; instead, Swinton read a statement at a news conference there that she attributed to this reclusive figure.

Now both Swinton and Guadagnino are ready to come clean.

“The answer to the question to me, ‘Are you playing Dr Klemperer in Suspiria?’ is always that Dr Klemperer is played by Lutz Ebersdorf,” Swinton told me last week in an email. Yet there is a more specific question she has been waiting for someone to put to her, “and curiously, to date, nobody has thought of it”.

That query, if anyone had bothered to ask, is “Are you playing Lutz Ebersdorf?” And the answer, Swinton said, is “an unequivocal yes”.

Of course, that begs another question. Swinton’s real identity does not augur some sort of gender-bending Suspiria plot twist, and while Klemperer spends much of the movie investigating the coven’s supernatural schemes, at no point does this elderly psychoanalyst shed his makeup to reveal that he is another character in disguise. So why was Swinton playing Lutz Ebersdorf?

“Undeniably, I would have to say, for the sheer sake of fun above all,” Swinton emailed. “As my grandmother would have it — a motto to live and die by — ‘Dull Not To.’”

Still, Swinton and her director had more in mind than just playfulness. Guadagnino had always conceived Suspiria as a movie about female identity, and to cast Swinton in the only significant male role, would ensure that “there will always be this element of femininity at its core,” Guadagnino said. “Being a film about the fantastic, it was important that we did not play by the book.”

Swinton added, “A psychoanalyst, or a psychiatrist with a sense of the unconscious, is someone who knows that in every delusion is an attempt to tell a truth.” Noting Klemperer’s preoccupation with a spouse he had lost in the war, she said, “Klemperer is inhabited by the phantasm of his lost wife: He is, in this crucial respect, ‘played’ by a woman. She dictates the rhythm of his life in the everyday texture of his bereaved loneliness.”

And while to say much more would be a spoiler, there is also a third, more monstrous character that Swinton plays in the final act, and Guadagnino intentionally conceived these three figures for her.

“This is a movie that is very connected to psychoanalysis,” he said, “and I like to think that only Tilda could play ego, superego and id.”

To aid Swinton in her transformation to Klemperer, Guadagnino hired the Oscar-winning makeup artist Mark Coulier. Though Coulier had previously put Swinton in old-age prosthetics for The Grand Budapest Hotel, and Swinton has played male characters before on film (most notably, in the 1992 Orlando) to do both at the same time would be a new challenge. In fact, the striking features that have served Swinton well in other transformations were of no use as Klemperer.

“Although she has a slightly androgynous look from sort of a fashion-model point of view, Tilda’s got a very feminine bone structure,” said Coulier, who thickened Swinton’s neck with prosthetics and built her jaw out to look heavier and more masculine.

While in character on set, Swinton preferred to be addressed as “Lutz,” and Coulier said that many of the extras and crew members on Suspiria had no idea who they were really looking at: “They were all like, ‘Is this a famous actor, Lutz Ebersdorf?’ They’d go on IMDb looking for him, and there wasn’t any information.”

To extend the mystery, then, Swinton herself wrote an IMDb biography for Ebersdorf: He was a retired psychoanalyst from Berlin who had never before appeared in a film, and conveniently had no plans to act again in the future. Swinton even conscripted Coulier to add a moustache to her makeup so she could upload a faux headshot to Ebersdorf’s IMDb page. (IMDb has since directed users to Swinton’s own profile.)

The ruse might have held longer had a paparazzo not snapped a photo of Swinton as Ebersdorf during production in Berlin, then sold it to US services two winters ago as a picture of Swinton in disguise. “Maybe there was a mole in the German crew,” Guadagnino said. “It did bother me.”

Though not everyone was paying attention at the time, as Suspiria began to near release, journalists started asking questions about the mysterious man credited as “Lutz Ebersdorf”.

“The intention was never to fool anybody,” Swinton said. “The genius of Marc Coulier notwithstanding, it was always our design that there would be something unresolved about the identity of the performance of Klemperer.”

Still, now that the secret is out, Swinton can’t help but voice one last, cheeky regret.

“Frankly, my long-held dream was that we would never have addressed this question at all,” Swinton said.

“My original idea was that Lutz would die during the edit, and his ‘In Memoriam’ be the final credit in the film.”

-The New York Times