In "The Serpent's Shadow" by Rick Riordan, the characters Ruby and Sadie Kane discuss troubling visions concerning unfamiliar gods and rival magical forces. Sadie's inquiry reveals her concern as she learns about potential threats to Egypt, highlighting the ongoing struggle the land faces from external entities. Ruby emphasizes the importance of remaining cautious, as Egypt's history is filled with challenges posed by foreign magicians and gods. This warning underscores a sense of urgency, urging Sadie to stay alert to any dangers that may arise from beyond their borders.