If you want to focus on from the series (like Cassie or Nell)
It had been three years since the Collapse—since the "Hungry" had turned the bustling streets of New York into a graveyard. He often thought of Cassie and the others, wondering if they were still hunkered down in their fortified sanctuary or if the world had finally caught up to them, too. "You’re brooding again," a voice called from the doorway.
As the first gray, shambling shape broke through the treeline, Peter took a deep breath of the cold mountain air. He didn't know if they would see the morning, but he knew they wouldn't go down quietly. "Until the end of the world," he whispered.
Down the hill, the perimeter bells jingled—a soft, frantic tinny sound.