Michelle Williams doesn’t so much impersonate Marilyn Monroe as suggest her in the entertaining bio-drama “My Week With Marilyn.” She doesn’t have Monroe’s overripe figure, or Kewpie doll lips. There’s va-va without the voom.

But in scene after scene, Williams “gets” Monroe — the sex appeal, the vulnerability, the sense of fear of discovery behind all that out-there sexual bravado. When she’s singing about starting a “Heat Wave” by “making my seat wave” — friends, you will believe it.

“My Week” is based on a memoir by Colin Clark, an upper-class lad who used family connections to land a go-fer job on the set of Sir Laurence Olivier’s film, “The Prince and the Showgirl,” a 1956 comedy that co-starred Monroe.

Clark (Eddie Redmayne) ingratiates himself with Olivier, played with a flint-edged gleam by Kenneth Branagh. Next thing he knows, the director and fading star have brought him in as third assistant director.

Over the course of the film’s production, Clark became the go-to intermediary in various Brits’ dealings with the mercurial, difficult and neurotic bombshell.

British TV director Simon Curtis (“Cranford”) and screenwriter Adrian Hodges concoct a fascinating milieu that gives us a minor revision of Monroe’s reputation.

If you’ve read any biography of Lord Larry and his Blanche Dubois wife, Vivien Leigh (Julia Ormond), you’ll be scratching your head at his patience and her sanity.

Neither seems accurate. But Branagh and Williams are worth the price of admission, the former “wunderkind” of stage and screen having a go at the pretentious Olivier, who referred to movies as “MO-see-un pictures.”

Williams, recreating a few of Monroe’s magical moments works the “dumb blonde” thing just the way Monroe did“Gee, Mr. Sir,” she says, not certain of how to address the knighted Olivier, “I could listen to your accent all day.”