It stars Frances McDormand as Mildred Hayes, a Missouri woman who rents three roadside billboards to draw attention to her daughter's unsolved rape and murder.

Her abusive ex-cop ex-husband Charlie confronts her about the billboards and ends up revealing that, shortly before Angela's murder, he had turned down her request to come live with him.

Willoughby spends an idyllic day with his wife, Anne, and their two daughters, and then commits suicide later that night to spare his family from watching him die slowly.

In the letter, Willoughby tells Mildred that she was not a factor in his suicide, asserts he was dedicated to finding Angela’s killer and reveals he secretly paid to keep the billboards up another month.

However, Dixon is inside reading Willoughby's letter to him, which advises him to let go of hate and embrace love if he wants to be a detective someday; he manages to escape the blaze with Angela's case file.

Unnerved that she retaliated against the wrong target, Mildred abruptly calls off the date, but James misinterprets her decision as embarrassment to be seen with him and leaves the restaurant incensed.

McDonagh described the billboards, which he presumed had been put up by the victim's mother, as "raging and painful and tragic" and was deeply affected by them, saying the image "stayed in my mind [...] kept gnawing at me".

[7][a] This incident, combined with his desire to create strong female characters, inspired McDonagh to write the story for Three Billboards Outside Ebbing, Missouri.

David Penix of Arden, North Carolina, subsequently bought the billboards and used the wood for a roof in Douglas Lake, Tennessee, though the messages are no longer legible.

[15] Town Pump Tavern in Black Mountain, which had been featured in The World Made Straight (2015), was closed for three days while filming took place inside.

The film also features songs by ABBA, Joan Baez, The Felice Brothers, the Four Tops, Monsters of Folk, and Townes Van Zandt.

[6] On February 27, 2018, it was released on 4K Ultra HD, Blu-ray, and DVD,[25] with Six Shooter, McDonagh's 2004 Academy Award-winning short film, included as a bonus.

The website's consensus reads: "Three Billboards Outside Ebbing, Missouri deftly balances black comedy against searing drama – and draws unforgettable performances from its veteran cast along the way.

"[35] Manohla Dargis, also writing for The New York Times, said in her review: "[McDonagh's] jokes can be uninterestingly glib with tiny, bloodless pricks that are less about challenging the audience than about obscuring the material's clichés and overriding theatricality.

"[37] Some took issue with its handling of racial themes, particularly surrounding the redemptive arc of Officer Dixon, whose alleged torturing of an African American prisoner before the events of the film is referred to several times.

In The Daily Beast, blogger Ira Madison III described the treatment of Rockwell's character as "altogether offensive [...] McDonagh's attempts to script the black experience in America are often fumbling and backward and full of outdated tropes.

"[38] Alyssa Rosenberg noted in The Washington Post that "[Dixon's] redemption doesn't merely defang his previous venomous bigotry; it softens Mildred's character development.

In this case, the flawed and problematic nature of all the characters (who are each bigoted, racist, judgemental, selfish, and thoughtless in their own ways) is actually one of the film's strong points: "We must therefore think about Three Billboards in the context of rape imagery.

It is a film that entwines everyone in its narrative: the local residents, the police, the news reporters as well as us, the spectator, as we are swung back and forth between the competing ethical interests of all the characters, each of whom is worthy and flawed, invoking empathy and open to negative judgment.