This film follows two of Samuel Beckett’s foremost interpreters, actress Billie Whitelaw and director Alan Schneider, as they rehearse and premiere “Rockaby,” Beckett’s haunting play written specifically for this project. Beginning with rehearsals in London through the opening performance in Buffalo, New York, various views of Beckett emerge as the play takes form, revealing the strong influence he has on modern theater and the complicated way his writing takes hold of an audience. Ms. Whitelaw won an Obie Award for her performance in “Rockaby.”