The Watchers by A.E.W. Mason

We kept along the ridge of hill towards the east of the island, and met no one, nor, indeed, were we likely to do. I could look down on either side to the sea. I saw the cottages on the shore of New Grimsby harbour on the one side, and on the other the house at Merchant's Point, and the half-dozen houses scattered on the grass at Old Grimsby, that went by the name of Dolphin Town, and nowhere was there a twinkle of light.

Tresco was in bed.