Water Memory by Vernay and Reynès

A new life begins for Marion when her mother inherits an old family house and decides to make it their new home. With its own private beach and a view of the sea, the house has all the makings of a happy new life. But when Marion discovers strange rock carvings nearby, and learns that a sinister-looking lighthouse watchman may be part of a local legend come to life, it becomes clear that things are not as idyllic as they seemed.