Rachel Reynolds scanned the playground for any signs of trouble. Unsupervised children. Bullies. Swarming insects.
    None. Just another day at the park for a dozen or so moms with their kids.
    Her gaze shot back to her son, four-year-old Aiden, who was playing on the other side of the waist-high fence, not even ten feet away. He climbed the plastic steps of the slide---the tallest one at the park---and stopped at the top.
    "Look at me Mommy!" His wide, brown eyes connected with hers and glowed with satisfaction.
    Rachel waved and wiped at the perspiration on her forehead. Even under the shade of the pine tree, the summer heat still felt sweltering. "I'm watching, honey."
    Just as he propelled himself down the slide, something hot whizzed past her arm. The smell of acid filled her nostrils. Pain sliced into her skin.