Final answer:
A crack in the roof from which a blood-red moon shines through can symbolize impending danger, mystery, or an omen in literature.
Step-by-step explanation:
In literature, a crack in the roof can symbolize various ideas depending on the context of the story. However, in the given scenario of a blood-red moon shining through the crack in the roof, it could be interpreted as a symbol of impending danger, mystery, or even an omen. The blood-red color of the moon adds to the ominous atmosphere and may foreshadow a significant event or change in the narrative.
Learn more about Symbolism in literature