What is 'A Simple Favour' about? The wild plot of Blake Lively and Anna Kendrick's new movie

It makes 'Gone Girl' look like a walk in the park.

By: Susannah Guthrie

A Simple Favour might be one of the most buzzed-about movies of 2018, but few people could tell you what it's actually about.

The curiosity kicked in big time back in March 2018 when the film's star, Blake Lively, deleted her entire Instagram bar one post and only followed a bunch of people named Emily Nelson.

She also changed her bio line to the chilling question: "What happened to Emily?"

So, months later, we still wanna know ...what did happen to Emily? Given the film's not out in Australia until September 13, we thought we'd help you out by supplying a very loose synopsis of what goes down.

Let's start by watching the trailer, which probably raises more questions than it answers...

And don't worry, we're not here to give you spoilers, we just want to give you some helpful hints so you know what you're getting yourself into.

For starters, the movie is based on the 2017 novel of the same name by author Darcey Bell and is directed by Paul Feig, the genius behind Bridesmaids and Knocked Up. Depraved comedy is his thing.

Anna Kendrick plays Stephanie, a chirpy single mother with a young son who spends her days organising her son's school events and doing regular food and crafts vlogs for her online community of mom fans.

This is Anna, who just so happens to be our October cover star (go buy it so you can find out about the three-year period where she refused to date anyone):

And this is Stephanie, who enjoys collared shirts, brightly coloured knitwear and baking:

Anna talked a little bit about Stephanie's difficult life in this interview, where she admitted she struggled to film certain scenes because they were so brutal:

Stephanie is harbouring a fairly fucked-up past and is pretty lonely because all the parents at school resent her for being over-eager, so you can imagine her delight when fellow school mum Emily — a glamorous enigma played by Blake Lively — shows a passing interest in her.

As their sons come together for regular play dates, Stephanie and Emily resort to regular drinking-and-debriefing sessions, where Stephanie gets to know Emily's handsome husband (Henry Golding), her high-powered job and her love of drinking, partying and sex.

Emily is a queen, but also a terrifying force. She dresses exclusively in sexy menswear, swears like a sailor, has an oil painting of one of her nudes on the living room wall and knows how to make a killer martini.

This is Emily:

We are equal parts terrified by her/obsessed with her.

Unfortunately, we don't get to enjoy Emily's bomb outfits for long because all of a sudden she vanishes with no explanation.

Her last request before her disappearance is for Stephanie to pick her son up from school and look after him while she handles a "work crisis". This is the 'simple favour' the film's title refers to.

What follows is one of the most unpredictable, disturbing and twisted rollercoaster rides of a plot we've ever seen in cinemas. Think Gone Girl and Girl on the Train, but on steroids. With a little bit of Riverdale and Pretty Little Liars thrown in for good measure.

Stephanie makes finding her so-called "bestie" her new life's work and, in doing so, becomes entangled in Emily's mess. And it's pretty goddamn messy.

Be warned: there's violence, VERY adult themes (think Game of Thrones-level debauchery), the language is fairly intense and there are some pretty gruesome scenes. It's also a bloody riot.

Blake makes for a seriously fascinating bad girl (aside from The Town, it's the first time we've seen her look a little rough) and Anna just slays every role she touches. Her physical comedy skills are unmatched.

It's another juicy role for our new favourite on-screen love interest, Henry Golding, who you'll recognise from Crazy Rich Asians.

This is him (making out with Blake):

Check out our interview with Henry below:

Keep your eye out for other killer cast members, most notably Girls star Andrew Rannells, who plays a hilarious judge-y school dad and has the world's best one liners.