Libby and the Highland Heist

After a tumultuous term in Paris, Libby and Connie are looking forward to a quiet Christmas. Along with Libby's aunt, Miss Mousedale, they are to spend the holiday at the Highland estate of Connie's family.
But before long they find themselves caught up in strange events. Missing paintings. Lights in the woods in the early hours of the morning. A hidden room behind a wall tapestry. And Connie's parents seem to be keeping an unhappy secret. Can the friends untangle the clues and solve the mystery?