The Mystery at Snowflake Inn (Boxcar Children #3)by Gertrude Chandler Warner

Grandfather is taking everyone on a special holiday trip to an old-fashioned New England inn. The Aldens have fun playing in the snow, ice-skating, and working puzzles. Then mysterious things start to happen at the inn, and the owner worries he'll have to shut down. Can the Boxcar Children find the culprit, or will their winter vacation be cut short?