Opening scene is quite literally of three dilapidated billboards (missing/disjointed frames) on a foggy day
Main character (Mildred Hayes) - a mother - is very assertive from the beginning, but has nervous habits (chewing fingernails) - has a kind of no-nonsense attitude
Formerly a church attendee
Divorced (has an ex-husband (Charlie), who is currently dating a much younger woman)
Ex-husband attempts to choke Mildred, and Robbie is threatens Charlie with a knife (which is slightly concerning, indicating history of past domestic violence that he's used to/knows how to react to).
Two children (Angela, and Robbie)
Seeking vengeance for daughter Angela, who was raped and murdered, with the culprit never being found - critiquing police force for lack of action (particularly in concerns to more trivial crimes)
Billboards are put up over the Easter holiday - clerk is reprimanded for letting it happen. Following Willoughby's death, the billboards are set alight (culprit is later revealed to be Charlie, while drunk) and Mildred futilely tries to extinguish it.
"How come, Chief Willoughby" - Willoughby, chief of the police force, also has pancreatic cancer, but commits suicide before he succumbs fully. Mildred's vendetta against him is a direct result of his lack of action in resolving Angela's murder.
Married to Anne Willoughby; who drops by Mildred's shop to give her a letter left by Willoughby post-suicide.
His replacement in the force happens to Abercrombie, who is African-American and who is not taking anyone's shit, given the racism prevalent in Ebbing's police.
"Everybody is with you on Angela. No one is with you on this" // "We're all on your side about this Mildred Hayes thing"
At the same time, people choose to turn a blind eye to things if it's not directly affecting them.
"The more you keep a case in the public eye, the better your chance of getting it solved."
The movie does take a bit of a jab at 'politically correct' terminology not fully resolving any institutional problems - "It's 'Persons of colour'-torturing business, these days, if you want to know."
~46:00 - an anonymous payment to cover Mildred's billboard fees for the next month, after Red (the shop clerk Red Welby) is intimidated into (finding a way of semi-legally) removing Mildred's billboard.
Payment is from Willoughby ("I gotta admit, Mildred, the billboards were a great fucking idea"), who is apologetic for never having resolved Angela's murder.
Dixon and Red Welby - who is forgiving, yet sorrowful towards the former's plight - end up sharing a hospital room...
"Still wanna put up the Willoughby one?" "Why not? He paid for it."
In more than one way.
Dixon overhears the intruder in Mildred's shop admitting to having raped a girl, noting his truck's numberplate, and starts a fight - risking himself (still in recovery from his burns) in order to retrieve a DNA sample
"Anger begets greater anger" - words of wisdom from Mildred's ex-husband's 19-year old girlfriend's book about polo. To me, this movie is reminiscent of the movie Memento.
Multi column
Three Billboards Outside Ebbing, Missouri ~3:00
Police Corruption/Racism ~12:00
"Mexican sons of bitches"
"I thought you only took out black dudes, [Jason] Dixon!"
"He tortured a guy in custody!" (allegedly no evidence, the accused still on the police force)
"Ex-wife beater"
After Willoughby's suicide, Dixon breaks into Red's building, brutalises him and pushes him out of the window before punching Pamela.
"Get rid of that black guy!"
A flashback to past days ~32:00
Flashback to Mildred's argument with Angela, who is a teenager at the time.
One Deer Outside Ebbing, Missouri ~44:00
The Just ~52:00
"Don't open the bag. Just tell telephone the boys"
One may consider Willoughby's fate justice ("the just") for Mildred's plight.
Hate never solved nothing... ~1:16:00
At the same time as Dixon is reading Willoughby's letter about needing to love and think to be a detective - to solve a crime - with the absence of hate, Mildred is taking her anger out on the police station; setting it alight with Molotov cocktails. (As the audience, we are already privy to his dreams of being a detective - just before Willoughby's death was announced, there is a scene of him playing around with a magnifying glass)
Dixon retrieves Angela's case file - which was already alight, stuffing it under his jacket to stop it from burning further - before falling out of the station windows and tossing it ahead of him to prevent further damage.
James covers for Mildred's arson by saying they were on a date the entire night (???)