Silent Night explained (including that ending) - Caution Spoilers
The world is facing imminent destruction from a lethal toxic cloud, and the UK government has issued "exit pills" to provide a painless death before the agonizing poison gas arrives. A Cast That Delivers
The film’s climax is notoriously bleak. As the gas approaches, the families retreat to their rooms to take their pills. In a shocking twist, Art refuses the pill and appears to die from the gas—only to open his eyes in the final frame. This ending suggests that the "experts" were wrong and that those who surrendered to fear may have died for nothing.
The story follows Nell ( Keira Knightley ) and her husband Simon ( Matthew Goode ), who host a group of old friends at their English country estate for one final Christmas. What starts as a typical gather-around-the-tree celebration—filled with petty bickering and too much prosecco—is actually a farewell party.