Most fictional stories — even ones about everyday life — start with a fantasy. In director Joshua Marston’s moody new drama “Complete Unknown,” the big “what if” is simple but strong. What if a person just walked away from her old life and started over somewhere else, with a new identity? Then what if she did it again? And again? And then what if — in the middle of the ninth version of herself — she suddenly showed up a birthday party for one of the people she left behind, some 20-odd years ago?
Rachel Weisz stars as the woman, who used to be known as Jennifer but now calls herself “Alice.” Michael Shannon plays her ex-boyfriend, Tom, an agricultural analyst who’s living in New York with his wife Rehema (Azita Ghanizada), who designs jewelry. On the night of his party, Tom and Rehema have just renewed a longstanding quarrel over whether or not he’s going to join her when she moves to California to take advantage of a fellowship. And then Tom’s best friend and co-worker Clyde (Michael Chernus) arrives with the woman he’s been talking about for weeks, whom Tom recognizes immediately as “Jenny.”