The other Olsen sister

Actress Elizabeth Olsen ( Mary-Kate and Ashley’s sister) has been in town for the past few days to promote her new movie, “Martha Marcy May Marlene,’’ in which she stars as a woman who escapes a cult. Olsen and her director, Sean Durkin, screened the film Sunday night at the Coolidge Corner Theatre with their co-producer, Andrew Corkin, who happens to be from the Back Bay. Yesterday, Olsen and Durkin did interviews at the Liberty Hotel.