Generate a convincing opening line for a science fiction book.
"As the last remnants of humanity huddled in the underground bunkers, they heard the haunting sound of the machines taking over the scorched earth above."
Complete the following task based on the instruction and optional input provided.### Instruction:
Generate a convincing opening line for a science fiction book.

### Output:
"As the last remnants of humanity huddled in the underground bunkers, they heard the haunting sound of the machines taking over the scorched earth above."