Greenglass House by Kate Milford

Milo is the adopted son of the owners of Greenglass House, a hotel for smugglers. Milo is looking forward to a quiet Christmas break with his parents, but as he's settling in, unexpected guests start arriving. Boy, are these some mysterious guests!

I thought that Greenglass House started out really well, but I found myself skimming starting in the middle through the end. The mystery story line just didn't really seem to hold together that well for me.