I get a little shivery every time I see the phrase 'darkness falls' in a novel — it’s like the author has just dimmed the lamps in the reader’s head and invited us to squint harder. For me, it usually signals a hinge: a literal nightfall, sure, but more often a moral or psychological dusk. When the text says 'darkness falls' the scene often shifts from clarity to ambiguity; characters stop seeing each other and start seeing themselves, or their masks, in a harsher light.
On a craft level, authors use that line to compress time. It can mark an ending of innocence, the start of a chase, or the moment secrets stop being secrets. In some books it feels very cinematic — lights go out, the soundtrack swells — while in quieter novels 'darkness falls' can be almost clinical, the narrator noting the change like a scientist. I’ve seen it act as foreshadowing (a storm of events) and as punctuation for a turning point in a protagonist’s arc. Think of it alongside scenes where windows are shut, doors locked, or a single candle is blown out; the phrase makes those images stick.
Personally, I tend to read those moments slowly, cup my tea, and let the sentence sit. It’s a cue to brace for emotional weather. Sometimes 'darkness falls' means danger, sometimes relief — a character collapsing into sleep after trauma. Either way, it’s one of those small, potent phrases that anchors the novel’s mood and tells you: something significant just shifted, and you should pay attention.