"How well do we know anyone? How well do we know people who we think are really close to us?" As director and executive producer Susanne Bier says, those are the questions at the center of HBO's upcoming limited series The Undoing.

Created and written for television by David E. Kelley (Big Little Lies), The Undoing is the story of Grace (Nicole Kidman) and Jonathan Fraser (Hugh Grant), an extremely successful married couple in New York whose lives are upended after "a violent death and a chain of terrible revelations," per the show's description from HBO.

The series reunites Kidman with Kelley, with whom she worked on Big Little Lies. "It was right after Big Little Lies and [David] had written the first two episodes and he gave them to me and said, 'Do you want to play Grace?' I read it and went, 'Oh my god, give me the next one," Kidman says with a laugh.

With Kidman, who also serves as an executive producer, on board as Grace, it was Bier who brought up the idea of Grant playing her husband. "Susanne said, 'I want Hugh Grant.' And I was like, 'We'll never get him,'" Kidman remembers. "I knew him socially but had never worked with him, so we were really fortunate to get him."

Grant's Jonathan is a children's oncologist, something Grant took to heart. "One of the things I kept writing down — and I make pages and pages of notes — but one of the things I kept coming back to was bedside manner," Grant says. "That sort of smooth and marvelous way a doctor approaches a patient, relaxed and calming and smooth and elegant, and in a way, too good to be true. A savior. I’ve always found that creepy," he says with a laugh. "I used that a lot and I think that’s kind of how he is in his whole life, his incredible ability to project calm and authority."

Jonathan will need that calm as, over the course of the six-episode series, the police work to piece together the events around the aforementioned "violent crime." And with each step closer to an answer, the characters will be forced to face, as the trailer puts it, "ugly truths."

"As much as it's a classic thriller with all these cliffhangers, there are really complex themes, particularly about choosing to see what you want to see and what we would choose to believe," Kidman says.

Bier adds, "You aren't quite sure who and how to trust any of them, which is almost like in real life. We've all bumped into people where we had that sense of that attraction to something which is slightly intangible and slightly inaccessible but still utterly fascinating."

As for Bier's earlier question of how well do we know anyone, she says, "The truth is that we never really know."

EW has the exclusive trailer for the series, which also stars Edgar Ramirez, Noah Jupe, Lily Rabe, Noma Dumezweni, Donald Sutherland, and more, above.

The Undoing will hit HBO on Oct. 25.

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