The antiphon for 21st December is O Oriens (O Radiant Dawn or O Dayspring):
Dayspring, Brightness of the everlasting light, Sun of justice, come to give light to them that sit in darkness and in the shadow of death!
O Oriens, splendor lucis æternæ, et sol justitiæ: veni, et illumina sedentes in tenebris, et umbra mortis.
Click here to hear it chanted by the Blackfriar Dominicans.
At the end of a horror movie is the dawn. Evil has ruled the night, but salvation comes with first light. This modern metaphor can help us to understand this title: Jesus, the Radiant Dawn, saves us who have dwelt in darkness, and banishes the horror of a life without grace.