The reason Myrna never sleeps is that she's busy dreaming up amazing adventures. Myrna, Firefighter Supreme, battles a forest inferno but kindly stops to give a raccoon a drink from her special fire-fighting hose. Trailing catnappers to a hangout for ""horse heisters, swine swipers . . . and bird abductors,"" Myrna the Peerless Private Eye takes each rescued pet home in her custom-made detecting van. After two more mini-adventures, Myrna and her brother (saved from the stormy sea in Myrna's Amazing Boatcar) are asleep when their mother comes to wake them in the morning. In her first book, Peterson has created an appealing, tongue-in-cheek action heroine who does good for others. O'Brien's characteristically comic b&w illustrations chronicle one very busy night. For readers, the only thing missing may be knowing Myrna when she's not operating in Walter Mitty-mode. Each episode repeats the same formula, and without offering a sense of Myrna as herself, the fantasy wears a bit thin.