Michelle Williams displays an uncanny resemblance to the screen icon in the film, which tracks Monroe during her 1956 visit to London, where she was filming The Prince and the Showgirl opposite Laurence Olivier (played by Kenneth Branagh). The chemistry between the two screen titans was notoriously tense during their movie match-up, and Monroe was on her honeymoon with her new husband, playwright Arthur Miller (Dougray Scott).
The week in question refers to the time, after Miller left London, that film set assistant Colin Clark (Eddie Redmayne) introduced Marilyn to some of the pleasures of British life in an effort for her to get away from the pressures of Hollywood life. (via ET)