Final answer:
The narrator's first encounter with Lady Madeline is a shocking and tragic event in the story.
Step-by-step explanation:
The narrator's first encounter with Lady Madeline in the story is a dramatic one. He, along with the character Roderick Usher, witness the sudden appearance of Lady Madeline in a horrifying state. She is covered in blood and appears to have experienced a violent struggle. Lady Madeline falls onto her brother and they both perish in the scene, leaving the narrator in shock. This encounter sets the eerie and disturbing tone of the story.