This is a class set of 15 books. Twelve-year-old Ellen and her younger brother, Corey, are excited about their overnight camp-out at the zoo, until they discover that they are locked inside with a desperate escaped convict. Iowa Children's Choice Award-1995-96. Interest Level: 5-8 Reading Level: 6.1 ATOS Book Level: 4.6 AR Interest Level: MG AR Points: 5 AR Quiz: 8937EN Reading Counts Level: 5.9 Reading Counts Points: 6 Lexile: 680L Guided Reading Level: V.