Signed - The Unknown: A Novel by Riley Sager, Hardcover

In 1926, five women disappeared from a remote island in Vermont. Now, one-hundred years later, it’s happening again.
Struggling actress Marin Keane is shocked when she lands a role in a major motion picture about the unsolved mystery of New Avalon, an island on sprawling Lake Faraday in Vermont. She’s even more surprised when she learns that the role requires a weeklong research trip to that very spot.
Because New Avalon isn’t your ordinary island. A century ago, it was a commune for spiritual mediums—until they all vanished in 1926. The only trace of them was five dresses hanging from the branches of an old oak tree in the middle of the island, one for each missing woman. Some locals say they simply left. Others think they were murdered. But the prevailing opinion, thanks to a diary left behind by one of the vanished, a young woman named Daisy Rue, is that a séance gone wrong conjured something supernatural that took them all one by one.
Not long after arriving, Marin and her castmates, including legendary actress Violet Wright and white-hot director Ronan Peters, begin to realize all is not right with New Avalon. They hear strange noises in the night and notice mysterious symbols left behind by the island's previous occupants. And after a sudden health emergency leaves Marin, Ronan, and the other actors stranded on the island, the disappearances begin again.