My eight-year-old granddaughter called me at exactly 1:58 in the morning and whispered that she felt too sick to stand. Less than twenty minutes later, I found her burning with fever on the hallway floor of an empty house, with a note from my own son telling me not to call anyone.

My name is Robert, and I had always believed I knew my son, Michael, well enough to recognize when something was wrong. That belief started falling apart the moment I saw my granddaughter’s name glowing on my phone in the dark.

I almost missed the call because I had been asleep. When I answered, Sophie didn’t speak right away. I heard her breathing first—shallow, uneven, frightening.

“Grandpa,” she whispered, “I feel really hot.”

I sat up and reached for my glasses. “Where are you, sweetheart?”

“At home.”

That confused me. Michael and his wife, Denise, had told me Sophie would be staying with Denise’s sister for the weekend because she had a mild cold. They were supposedly taking her ten-year-old brother, Carter, on a short birthday trip.

“Where’s your aunt?”

Sophie didn’t answer.

“Where’s your mom?”

Another pause.

“They left.”

I was already getting dressed. “Is Carter there?”

“I don’t know.”

That scared me more than anything she had said. I told her to stay on the phone and promised I was coming. Michael lived about fifteen minutes away. I remember almost nothing about the drive except checking again and again that Sophie was still breathing, while forcing my voice to stay calm enough that she wouldn’t hear how terrified I was.

When I reached the house, the driveway was empty. I used the emergency key Michael had given me years earlier. Inside, the kitchen light was on. A glass of water sat near the sink. One of Carter’s sneakers lay sideways in the hallway.

Then I saw Sophie. She was curled on the hardwood floor in pink pajamas, her cheek pressed to the wood, her hair damp with sweat.