This mystery, which begins on the 14th floor of a New York house apartment where Fiona, from London, goes to join her long absentee writer-father, ends on the 15th floor where a spy ring has been operative. In between Fiona has had the unnerving experience of finding herself alone--her father has disappeared--being followed by strange men, and finally being held by, but escaping, the spies whom her father had tried to expose. The story, a little underweight to begin with, is forcefed with activity by the close-- her father is found, amnestic, in a hospital; and there's her own new romance. But there's lots of detail about seeing and sightseeing in New York (and Washington) and the American setting should extend the readership. Congenial.