Low Point

(cue some sad, low-energy pop song)

This is the point of the story where, true to its name, the atmosphere is unhappy, or "low". In the Low Point of the story, the Hero is feeling as if they can't possibly win, while the Villain is just the opposite — being so close to victory, they can't help but feel excited. The Low Point can be short-lived, being the length of a Sad Montage, or it can be drawn out to a longer duration. In a nutshell, the Low Point is when the good people feel bad and the bad people feel good.

The Low Point signals the nearing of the Climax as that's the natural progression of stories with a Happy Ending. If it's a story with an Unhappy Ending, this is where it ends before the Villain wins.