A mongrel pup helps two children unmask a clever deception! Kerry and Mark get a special excuse from school to spend ten days in Quebec with their father. From the moment they step into the hall of the rooming house where they are to stay, though, they have a sense of things not being quite right. Kerry hears sounds of crying; her sweater disappears and reappears in a mysterious manner. The children receive a strange communication, and the landlady behaves in a most unfriendly way. All of this adds up to a baffling problem that the children set about solving. There are other things to do in Quebec besides solve mysteries, and Kerry and Mark find time for sight-seeing and for making a new friend - who turns out to be helpful in their job of detection... Here is a timeless story that is just right for the reader who loves mysteries!