Yellow Cay (2020)

From publisher blurb:

Sometimes the people on the lake can be a bit literal. They named Yellow Cay because of the bushes that grow bright yellow flowers all the year round, showering the island with golden petals.

Yellow Cay lies a good hour’s rowing into the great lake. Its shores rise steeply from the water, and it is surmounted by two great, wooded peaks. A small fishing village nestles under a tall tower, from which a light beams into the darkness to warn lake-sailors of the shoals nearby.

But it's the people who make Yellow Cay interesting. What are they hiding? For hiding something is exactly what they seem to be doing...