Is there anything Michelle Williams (2010's "Blue Valentine") cannot do? In one film after the next, she creates such sumptuously vivid, uncompromisingly authentic characters that even if the script were to let her down, her work alone would ensure that there's not a lick of artifice in anything she does. In "My Week with Marilyn," based on both the title book and "The Prince, the Showgirl and Me" by Colin Clark, Williams challenges herself on an entirely different level by slinking into the iconic role of a real-life person—none other than Marilyn Monroe. This is not a cheap impersonation or an example of paper-thin mimicry, either, but an open-hearted, fully intuitive embodiment of the troubled woman behind the legend. Sure to shed insightful light on a figure most people today are probably only familiar with from photographs and classic film scenes that have since been lampooned to death, "My Week with Marilyn" is nevertheless but a snapshot of the artist when the jury's still out on whether or not a more conventional biopic might have been preferable. At the same time, what director Simon Curtis and screenwriter Adrian Hodges reveal is suggestive enough in its own right to the debilitating issues and addictions that ultimately led to Monroe's premature demise just a few years later.

Just out of university, 23-year-old aspiring filmmaker Colin Clark (Eddie Redmayne) scores a major break when he is hired by Sir Laurence Olivier (Kenneth Branagh) to help in the 1956 shooting of romantic comedy "The Sleeping Prince," retitled "The Prince and the Showgirl" before release. Starting out as a third assistant director—a glorified title for an on-set gopher—Colin quickly finds himself in the position of being Olivier's go-to guy as the director/performer struggles to make it work between himself and his chosen co-star, one Marilyn Monroe (Michelle Williams). Marilyn is a beyond-popular media starlet usually seen exuding confidence when she's out in public. Behind closed doors, however, she's a vulnerable mess of nerves and eccentricities, coddled by personal acting coach Paula Strasberg (Zoe Wanamaker), constantly late to the set at England's Pinewood Studios, and convinced that she's never good enough. Watching dailies of her performance, filled with line stumblings and messy bloopers in between sporadic successful takes, a producer muses, "When she gets it right, you don't want to look at anyone else." To arrive at that point for the length of the shoot, though, will severely test his patience and nerves. And for what? Ultimately, the aging Olivier will have to face the bitter truth about the slight, mostly forgettable picture he's making. As veteran performer Dame Sybil Thorndike (Judi Dench) tells Monroe, "He's a great actor who wants to be a film star, and you're a film star who wants to be a great actor. This film won't help either of you."

If 1957's "The Prince and the Showgirl" ended up being little more than a footnote in Marilyn Monroe's acting career, it does serve as ideal fodder for "My Week with Marilyn," a sort of limited-scoped "exposé-in-the-life" centering around the making of said film, as seen through the eyes of Colin Clark. The ins and outs of moviemaking in the 1950s are enthralling, if a little streamlined, pinpointing the loose camaraderie and sometimes raw emotions that come with making things work in front of the camera (and if they don't work, well, there's always the editing room to rely upon). The timeframe of the story is longer than the movie's title suggests, the symbolic "week" referring instead to Colin's fleeting bond with Marilyn, whom he is warned early on frequently shows men attention, makes them feel special, and then abruptly moves on. The 30-year-old Marilyn does not take a serious romantic interest in Colin—though she does comment that he's the first person she's ever kissed that's younger than her—but he is exactly the companion she needs as she struggles to cope with the foreign locale she's in, the loneliness she feels, and the repeated doubts she has about her worth as a performer. Whereas most people are predisposed to view her as an object, or a means to an end, Colin sees the soul beneath Marilyn's outer beauty, and she likes that he sees it.

Michelle Williams is almost certain to receive her third Oscar nomination for her outstanding work here. The very thought of playing Monroe must have been intimidating bordering on horrifying, but Williams doesn't allow even the vaguest of trepidations to show through. Her turn is complicated and layered, bouncy (as in her musical performance of "Heat Wave" that accompanies the opening credits) and tragic, the persona she exhibits alternating between warm and uneasy. Trying to please everyone while a prisoner of her own hang-ups, Marilyn's tough but sympathetic portrait is one that Williams doesn't miss a beat on. As the ambitious, wet-behind-the-ears Colin, Eddie Redmayne (2011's "Black Death") is a disarming protagonist, becoming something of a go-between in handling Monroe's and Olivier's rocky filming relationship. He's a joy to follow, and it's a good thing, too, since he's in nearly every scene. As Sir Laurence Olivier, Kenneth Branagh (2008's "Valkyrie") affectingly finds the self-involved regret of a man in the twilight years of being able to pull off a film's romantic lead. The savvy supporting cast, each making impressionable marks, include Judi Dench (2011's "J. Edgar") as the dignified Dame Sybil Thorndike; Emma Watson (2011's "Harry Potter and the Deathly Hallows Part 2") as fetching wardrobe girl Lucy, whom Colin takes a shine to; Zoe Wanamaker (2001's "Harry Potter and the Sorcerer's Stone") as Marilyn's method acting coach Paula Strasberg, and Julia Ormond (2008's "The Curious Case of Benjamin Button") as Olivier's wife Vivien Leigh, who has had to stand by and watch her intended part go to the still-youthful, more popular Marilyn Monroe.

In "My Week with Marilyn," Ms. Monroe is neither aloof nor indifferent, but she also has plenty going on that doesn't involve Colin. Their time together is special, but exists in its own time and place, without a future. That's how it seemed to always be for the superstar, at odds over who she could trust and who was only interested in what he or she could get out of being close to her. Unfortunately, she wasn't always the best judge of character. What "My Week with Marilyn" captures accurately is the mystique of this large-than-life personality and the compassion to see her as more than a face and a body and a baby-doll voice. At its center, making all of this a reality, is Michelle Williams' mesmerizing tour de force. It's one thing to get down Marilyn Monroe's look and sound. It's quite another to make her human.