An engrossing story about the choices in life that we make — and don’t make — with award-worthy performances by Rachel Weisz and Michael Shannon.

Complete Unknown directed by Joshua Marston. At the Kendall Square Cinema, Cambridge, MA.

Rachel Weisz in a scene from “Complete Unknown.”

By Neil Giordano

The hypnotic opening sequence of Complete Unknown, a riveting new independent drama from director Josh Marston (Maria Full of Grace), blithely tosses out the pieces of a puzzle. A jagged march of short scenes suggest a life: a woman (played by Rachel Weisz, although barely recognizable in some cases) is seen in ever-changing outfits and hairstyles; she is involved in a variety of jobs and activities. The clips jump from time frame to time frame and country to country. In one vignette she’s a surgical nurse, then she’s a prospective tenant, a magician’s assistant, a maternal figure warmly embracing a child. This strategy makes us curious about when and where and how she did all of these things. Yet we’re also off-balance, sensing that there are more disruptions to come.

After the opening montage, the woman enters the story, though slowly, indirectly. We first meet her as “Alice,” a mystery woman who eventually maneuvers her way into a dinner party. There she beguiles all the guests with her wit and breadth of experiences. The partiers (like the viewer) are mesmerized by “Alice,” content to listen to her every word and opinion, even falling silent to hear a recording of frogs recorded on her phone.

These opening scenes are reminiscent of Six Degrees of Separation, the John Guare play and film of the same name. Complete Unknown explores how a hyper-magnetic presence can disrupt the normal rhythms of life in an intelligent if complacent group of characters. Like Paul, Guare’s central character, “Alice”’s identity is slowly deconstructed, throwing the guests into various stages of suspicion and hostility. Tom, the party’s co-host, immediately senses that something is afoot the moment he sets eyes on “Alice.” He blanches, seeming to recognize her.

Who else but Michael Shannon could play Tom so well? The actor’s soft, subtle facial expressions convey a mix of knowledge and confusion brilliantly. When he’s finally alone with the woman during a lull in the party, Tom poses a question that punctures the woman’s enigmatic bubble: “What are you doing here, Jenny?” Its simplicity hints at their past while it also reveals her real name (though we are still left wondering).

The story then pares down to these two characters, Tom and Jenny, as she explains herself and her absence from the man’s life for fifteen years. Her adventures, generated by her ever-changing identity, provide an ironic foil to his conventionality. Tom, a steady-Eddie environmental policy wonk, is the yin to her yang. He has settled into a comfortable life of routine, asking little from his career and marriage to his beautiful wife, yet bothered by feelings of discontentment he needs to repress. Hovering between agony and anger, Tom listens to Jenny extolling the merits of her philosophy of constant change. He slowly becomes more sympathetic, understanding if not agreeing.

A mid-film episode, with cameos from Kathy Bates and Danny Glover as an aging couple, gives Jenny the opportunity to demonstrate the ease with which she can deceive others, instantly taking on a new identity in order to befriend new acquaintances. Tom carefully watches her performance art — with anxiety but also amazement — until he, too, becomes part of the act.

The film’s changing settings deftly mirror Tom’s evolving judgment of Jenny. From the early confines of the party, a bit too claustrophobic for Tom, who is worried about important changes taking place in his marriage, then to a music club where he’s granted more room to move about, and then to the open streets of Brooklyn. With each change in location the camera scampers around more freely. The final episode embraces movement — train rides and hikes in the woods during the middle of the night. For Tom, breaking boundaries is simultaneously exciting and horrifying; he literally changes clothes (becomes another self) to follow Jenny, letting himself be uninhibited for at least for a precious few hours.

The story’s exploration of the power of choices and the lure of metamorphosis deepens with each episode, generating profound questions. Is the self stable, a known entity throughout time? Or do our choices create identity? At the same time, Complete Unknown becomes, quite subtly, an examination of gender expectations; the cobwebbed stereotype of the adventurous male and domestic female are turned on their heads. What does it mean for a woman to leave everything behind, her lover, her family, her entire identity? Is it different than it would be for a man? Should it be? Director Marston is content to examine these questions by way of Tom’s quiet catharsis — thankfully, no bold statements or simple platitudes are provided.

The performers here are superb. Weisz, as Jenny, clearly savors the chance to play a powerful female chameleon. Her secretive character stands as a counter to lives that are structured and ordered. Still, Jenny’s obsession with transformation, splendid as it is, takes a toll. There is a price to be paid. Weisz’s Jenny is confident about the value of never staying still, yet there are flickers of ambivalence, minute expressions of guilt, anguish, and loneliness. Like Tom, we can’t take our eyes off of her. No matter how various Jenny’s selves, she’s a singular sight to behold.

Neil Giordano teaches film and creative writing in Newton. His work as an editor, writer, and photographer has appeared in Harper’s, Newsday, Literal Mind, and other publications. Giordano previously was on the original editorial staff of DoubleTake magazine and taught at the Center for Documentary Studies at Duke University.