I remembered my first sight of Sylvie, on the dock. She had been eating a chocolate bar. “Sylvie liked sweets and chocolate,” I said.

“You’re right, Nick! Yes. She loved chocolate. She could never resist it. When Mark was going out with her, he took her on a tour of a chocolate factory. She even ate the tickets.” Tim frowned. “But what’s that got to do with anything?”

“There was a piece of silver paper on the floor in her room. I think it was the wrapper off a piece of candy or a chocolate. Don’t you see? Someone knew she couldn’t resist chocolate—so they left one in her room. Maybe on her pillow.”

“And it wasn’t almond crunch,” Tim muttered darkly.

“More likely cyanide surprise,” I said.

We got into bed. Tim didn’t want to turn off the lights, but a few minutes later, after he had dozed off, I reached for the switch and lay back in the darkness. I needed to think. Sylvie had eaten a poisoned chocolate. I was sure of it. But had she been given it or had she found it in her room? If it was already in the room, it could have been left there before we arrived. But if she had been given it, then the killer must still be on the island. He or she might even be in the house.

There was a movement at the window.

At first I thought I’d imagined it, but propping myself up in the bed, I saw it again. There was somebody there! No— that was impossible. We were on the first floor. Then I remembered. There was a terrace running along the outside of the house, connecting all the bedrooms.

There it was again. I stared in horror. There was a face staring at me from the other side of the glass, a hideous skull with hollow eyes and grinning, tombstone teeth. The bones glowed in the moonlight. Now I’ll be honest with you. I don’t scare easily. But right then I was frozen. I couldn’t move. I couldn’t cry out. I’m almost surprised I didn’t wet the bed.

The skull hovered in front of me. I couldn’t see a body. It had to be draped in black. It’s a mask, I told myself. Someone is trying to frighten you with a joke-shop mask. Somehow, I managed to force back the fear. I jerked up in bed and threw back the covers. Next to me, Tim woke up.

“Is it breakfast already?” he asked.

I ignored him. I was already darting toward the window. But at that moment, the moon vanished behind another cloud and the darkness fell. By the time I had found the lock and opened the window, the man—or woman, whoever it was—had gone.

“What is it, Nick?” Tim demanded.