Returning an overdue library book is sometimes an unpleasant experience, but seldom a life-or-death escapade--as of course it proves to be for superheroine Vesper Holly. Once again, Alexander works his magic: in returning a priceless manuscript (borrowed years earlier by her father) to its remote North African home, Vesper faces treacherous mountains, deadly desert, and dangerous characters--including slave merchants and a corrupt, bloodthirsty governor. As ever, Vesper is accompanied by her bumbling guardian/biographer, Brinnie Garrett; also as ever, she makes plenty of friends: Colonel Marelle of the French Foreign Legion; Maleesh, a poor street-magician who finds good fortune and a sweetheart on the journey; and the fierce, blue-skinned An-Jalil es-Siba, chief of the desert Tawariks. Figures from previous books reappear, including arch-fiend Dr. Helvitius, whose plans for world domination now hinge on an experimental flying machine he forces Vesper to test fly (the year is 1874). With her usual panache, Vesper saves lives, settles an ancient feud, sends Helvitius packing, and even returns the library book before going home to Philadelphia--where the reader is left to imagine what she'll do with her combined engineering skill and new appetite for powered flight. Fine, comic high adventure; beguiling jacket by Trina Schart Hyman.