An ill-structured entanglement with sibling rivalry--to the extent that the point of the story is obscured. The book begins, baldly, ""I want a baby brother. His name will be Kate, just like me""; but it's not until near the close that we learn that a baby is in the offing, and it's not until after narrator-Kate promises imagined baby-Kate all sorts of indulgences that we learn their genesis: her grievances against an older sister, Emily. Then--following the inexplicable appearance of funny-looking ""Mrs. Wetherbee"" (not recognizable, then, as a baby nurse)--we flash back to big-sister Emily's latest unfairnesses to Kate. . . which lead into a third time-frame, the one in which the news comes that Mom has had a baby. The only reason to stick with this is to find out what-all's going on--and that's not a good enough reason for kids.