The film stars Keira Knightley, Matthew Goode, Roman Griffin Davis, Annabelle Wallis, Lily-Rose Depp, Sope Dirisu, Kirby Howell-Baptiste, Lucy Punch, Rufus Jones and Davida McKenzie.

The film features a group of friends who reunite for one final Christmas right before an ambiguous apocalypse will wipe all of humanity out.

Married couple Nell and Simon host a yearly Christmas dinner at their country estate for their former school friends and their spouses.

It is gradually revealed that because of an imminent environmental catastrophe in which a gigantic rolling poisonous gas cloud (which follows minutes after numerous smaller green tornadoes that are generally considered as heralds of the upcoming danger) is killing most life forms, the British government has issued suicide pills for a quick and easy death before the cloud hits Britain.

Nell, Simon, and the rest of their friends have made a suicide pact to take the pills and give them to their children.

However, while James agrees with his friends over the decision, his young wife Sophie has recently discovered she is pregnant and is still unsure whether to take the pill.

There are several confrontations during the night: Kitty is given a doll that resembles her, and she hugs her father, but refuses to hug Sandra even though she begs her to; Art finds the act of gift giving ridiculous, so he lashes out at the adults and runs from the room; Sandra tells James she had loved him when they were in school and wondered why they never had sex; Tony gets visibly upset at her admission and claims he has never made a mistake, at which point Bella says they once had sex before he got together with Sandra; Alex feels left out during the festivities, which causes her to drink too much and pass out in her bed.

Lily-Rose Depp, Kirby Howell-Baptiste, Davida McKenzie, Rufus Jones, Sope Dirisu and Lucy Punch were cast the next month, with filming beginning on 17 February.

The site's critical consensus reads, "Spending time with these characters can be a lot to ask, but Silent Night peers into the abyss with admirable aplomb.