Cameron's delicate time fantasy is set in a San Francisco museum furnished with the transported appointments of an old French castle, right down to the ghost of Domi, a young girl who inhabited the castle in Napoleon's time. Thus the museum, tangibly evoked, functions as a seamless link between the already introspective everyday life of lonely, intense Nina on the one hand and the ghosts' 170 year-old burden on the other. On reflection the Domi-Nina intersection concerns a disappointingly ordinary problem: Domi's father was unjustly accused and executed by Napoleon, and as the ploddingly scholarly Mrs. Stayne at the museum is now writing his biography Domi enlists Nina's help in uncovering evidence that will clear him of the charges. This accomplished, the ghost of course fades from Nina's company forever. Nina's new friend Gil, a solitary boy consumed by his ""project"" of investigating the meaning of time, proves an effective device for exploring the theoretical implications of the girls' encounter; thus he quotes Bergson, his parents, and others on the subject of time and conducts rational discussions of such subtopics as prophetic dreams (experienced by both Domi and Nina). Sometimes the discussions illuminate the adventure less than they weigh it down with reminders of the author's intent, and when even Nina's new landlady enters quoting a passage about existing out of time, it's hard to suspend incredulity. Nevertheless, the Gil/Nina/Domi relationship constitutes the center of an impressively executed pattern -- and, incidentally, a far more ambitious use of a museum background than Claudia's detective work in Konigsburg's Mixed-Up Files.