The publicist's plea was simple yet complicated: If you talk with Rosamund Pike, avoid spoilers about her character in "Gone Girl."

So noted. But that character — a wife who goes missing and narrates the erosion of her marriage in flashback — is the whole point of Pike's richest screen portrayal to date. It shows her in a deeper dimension, with complex and contradictory emotions. She seems an illusion at times, an enigmatic piece of fiction more than a real woman. Can we talk about this?

"I think you've found a way to explain it," Pike said by phone from New York. "It's always interesting what a filmmaker sees in you, what you're called upon to produce, whether your comedic side or your romantic side. And in this, it was all my sides and a few more."

Pike came in as an outsider to David Fincher's screen adaptation, a proper British woman whose best-known work draws on her cool reserve. She was icy Miranda Frost in "Die Another Day." In "An Education," she played the sweetly ignorant girlfriend of Dominic Cooper's con man. Her stunning beauty made her the perfect Jane Bennett in "Pride and Prejudice," and that regal bearing served her warrior goddess in "Wrath of the Titans."

"Gone Girl" plops Pike into the Missouri humidity, where she sweats out charades of human behavior.

"I enjoy talking about the film," she said of the press regimen she is enduring. "I don't enjoy so much talking about myself. It will be more exciting after the film is released and we don't have to hide all the twists and ends anymore."

In Fincher's head

Pike, 35, was not lusting after this role. If she had been, it wouldn't have done much good, she said. Fincher has own way of casting that has little to do with auditioning or eloquent appeals from actors who insist that they would be perfect.

Fincher had Pike in his head when he called her. Eventually, the actor realized she was under serious consideration. They talked frequently about the character of Amy Dunne, how they would put her on screen and how Pike would handle the transformation of becoming an American.

"It was a process where he sort of dissected me totally over a period of weeks, over Skype, in person and on the phone," Pike said. "And of course, now I realize that is the way he works."

Pike worked with a dialect coach to erode her Queens English, reaching the depths at one point in the film of speaking in Ozark Hillbilly.

"It's not just changing your voice, it's changing your whole attitude," she said. "I saw a clip of a talk show this morning and I thought, 'God, I am so English.' You have to lose all that when you are doing a part like this."

As she searched for types and models to draw upon for the role, Pike made a curious discovery.

"I looked at Jacqueline Kennedy as a role model," she said. "There was something unknowable about that woman. Everyone wanted desperately to know that woman, and I feel that nobody really, truly did. Nobody really knew what was going on in that marriage."

Pike looked at pictures of Kennedy being hounded by paparazzi and imagined being in the skin of someone who danced a constant tango with her public image. Pike superimposed some of that complex obsession with image and privacy on Amy.

"It seems odd, but it was very helpful," she said of her ruminations about Kennedy.

A Brit in the colonies

Pike didn't really know any of her co-stars when "Gone Girl" began shooting. Neil Patrick Harris was instantly approachable and "lovely to work with." She had intimate scenes with Harris and Ben Affleck but deflected any gossipy chatter about how the filming went.

"That's your job as an actor," she said of getting mostly naked and hitting the bedsheets. Interestingly, she said that she and Affleck didn't get to know each other too well in part because their screen marriage benefited from some sense of remove.

"We didn't become so pal-y that we couldn't be convincing in the more toxic side of the relationship," she said.

Being British also helped because Fincher wanted from her a sense of isolation — that her character had been uprooted and planted in a strange place.

In "Gone Girl," Amy is a fish out of water, a native New Yorker transported to Missouri after she and husband Nick lose their jobs and retreat to his hometown. That alienation is an important element of her character.

This isn't to suggest Pike retreated to her trailer every day and never came out to play. She kicked around Cape Girardeau, Mo., a small river town near the bootheel, doing a little antiquing, grabbing coffee and making regular trips to Andy's Frozen Custard.

"I'm like a child in a candy store when I go to any new state in America," she said. "I love feeling the difference and realizing you have as much variety as we have in Europe."

What will be, will be

Pike is not impressed with suggestions that "Gone Girl" will be her breakout moment. She hopes so, she'd like that, but she also knows that the ball has left her court. It is up to audiences, critics and producers.

"I have been told before that things will change and they haven't," she said with a laugh. "I've had great moments and disappointments. This is certainly a great moment."

Her next production will be her second baby, in November. "Gone Girl" joins "Hector and the Search for Happiness" (in which she stars with chum Simon Pegg) in the public imagination. Another British comedy, "What We Did on Our Holiday," does not have a U.S. release date.

"If people do see a different side of me in 'Gone Girl,' and other great filmmakers want to work with me, that would be the goal," she said. "I would like to be pushed like I've been pushed by David."

Graydon Royce • 612-673-7299