On the night of the blue moon when mermaids are said to gather on a sandbar in the Gulf of Mexico, ten-year-old Keeper sets out in a small boat, with her dog BD and a seagull named Captain, determined to find her mother, a mermaid, as Keeper has always believed, who left long ago to return to the sea. Interest Level: 5-8 Reading Level: 4.7 ATOS Book Level: 5 AR Interest Level: MG AR Points: 8 AR Quiz: 137052EN Reading Counts Level: 4.7 Reading Counts Points: 13 Lexile Measure: 770 Fountas & Pinnell: U.