This well-written, believable book will appeal to thriller fans because of its good characterizations and horror elements that are never out of bounds. A summer job as companion to weird old Mrs. Cottler (who lives on Fear Street) becomes upsetting to Mayra, and she begins to sleepwalk at night after having nightmares. The job really becomes frightening when Mayra's best friend is mistaken for her and is nearly killed in an automobile accident. Although the real villain and his machinations are rather superimposed, Stine writes a good story. Teens will love the action; librarians will love the lure for slower and nonreaders.