The View from the Lighthouse by Melody Carlson

The View From the Lighthouse (The Miracles of Marble Cove, Volume 1) - Diane Spencer has just moved to Marble Cove. She intends to write a book.  Walking on the beach, she comes across an injured dog stuck in the rocks.  As she settles into her new life she becomes friends with Margaret Hoskins, who is opening a gallery in town; Shelley and Dan Bauer a young couple with children, struggling to make ends meets, and Beverly, Mr. Wheeland's daughter, who comes up from Boston on weekends.

All three women find that they have something in common.  They also share that they have all seen a flash of light from the local lighthouse Orlean Point.  All three are interested in the mystery and want to find out what causes the flashes from a non-working lighthouse.