While camping on a small lake in Michigan, Jacob and his cousins play a prank to scare Jacob’s little brothers. When Jacob refuses to show remorse, his grandpa warns him that his deeds may come back to haunt him. When Jacob finds a lost treasure map, his grandpa tells a tale of pirate children who once roamed the lake. He warns the boys that the pirates disappeared long ago while hiding their ill-gotten plunder. Jacob and his cousins set out to find the treasure and to discover the truth behind grandpa’s story.