Smoke alarm

He woke up in the middle of the night because the smoke detector was beeping. Beep, beep. A tiny, squealy sound. He got up and changed the battery. Then he went back to bed, and lay there, thinking about the sheep who were grazing in the grass by the river, and how they were supposed to swim across, and then one of them drowned, and then the second drowned, and then the third...