'The Wolverine': The Secret Behind Jean Grey

Famke Janssen tells MTV News why her role was a secret for so long.

For months and months leading up to the release of "The Wolverine," Famke Janssen repeatedly told the press that she did not reprise her role as Jean Grey in the "X-Men" spinoff. But after she turned up in the trailers for the film, Janssen offered a mea culpa to MTV News' Josh Horowitz for lying about her participation.

"I sincerely apologize, but I was sworn to secrecy," Janssen told Horowitz. "I had no choice but to lie. Don't ask me any more questions," she said with a laugh.

Janssen said that she undertook the role with great secrecy, although she was worried that just the process of going to the set -- which required an extremely long plane ride around the world where she might be spotted -- would spoil the surprise for fans. "The studio called me and said it's a big secret -- and we want to keep it a secret," she said. "It was a lot of hurdles to go through but we went through all of them, swimmingly. I was even able to lie to you and many other people, which is terrible, because I'm not a liar."

Although she acknowledged that it had been six years since she played the role of Jean Grey, Janssen said that it felt incredibly comfortable. But at the same time, she observed that the character always managed to be different in each film where she portrayed the character. "It's a different Jean Grey, and you know what? I'm lucky, because I've been a different Jean Grey every single time I've come back," she admitted. "I died at the end of [X2], I'm back as the Phoenix in 3, and all of a sudden now I'm back in my nightgown in dreamlike sequences.

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"But yet the moment I got off of that 20-hour journey, and I slipped into my nightgown and into bed with Hugh Jackman, it was as if we hadn't left one another," she revealed. "It's really kind of fun to play around with this attraction that's been between these two characters for all of these years."

"The Wolverine" opens in theaters nationwide July 26.