Ghosts of Greenglass House (Greenglass House, #2)

Welcome back to the irresistible world of Greenglass House where thirteen-year-old Milo is, once again, spending the winter holidays stuck in a house full of strange guests who are not what they seem. There are fresh clues to uncover as friends old and new join in his search for a mysterious map and a famous smuggler’s lost haul.