Mark's seven finely crafted short stories offer variously glancing-to-steady glimpses of the darker side of children's psyches or childhood experience. On a park outing, a girl spooks her small, overprotected charge's imagination with irresistible tales of leopards, poison, and the like. Another little girl charms warts in her rundown garden-shed laboratory. A little boy whose ""Mummy's going to have a baby"" retells ""The Three Little Pigs"" so the wolf triumphs. (""Three babies look like three little pigs,"" he announces.) And a truly sinister little boy (""Let's play hangman,"" he proposes to his new friend) chills the neighbors with his Guy Fawkes ""guy."" Two of the stories deal with kids' powerlessness at school: In one, a girl is reduced to helpless defeat by the power struggle between two teachers. But the tables are turned in the book's last and longest and most upbeat stow, in which another girl, on a holiday from her high school, drops into the one in her aunt's community and plays havoc with its typically repressive and arbitrary rule structure. Delicately constructed within the modern short story form, these pieces haven't the power of Mark's compelling novels, but they are subtle and swift in transmitting their own insidious vibrations.