This starts when Kim's mother takes a job, leaving sixth-grader Kim with the after-school care of little brother Willie, and putting off (for want of time) the purchase of the puppy Kim has been promised for ""some day."" Resentful, Kim haunts the local pound, does acquire a puppy, and involves Willie in a conspiracy whereby Misty is boarded--just till Mom can be prepared--with old Mrs. Mac who does odd jobs to supplement her social security. The deception takes its toll, especially as Kim must pay Mrs. Mac twice what she herself gets for baby-sitting Willie; and at last when Mrs. Mac has a middle-of-the-night heart attack the whole scheme is uncovered. Kim's noble gesture at the end--giving up Misty to console Mrs. Mac, who must now go off to her daughter in Ohio--is both convenient and sentimental; but never mind. Kids will identify with Kim's desperate efforts, in the context of a generally together family, to keep her parents at bay. And there's a Judy Blume-ish veracity (without Blume's shallow identification) to the sixth-grade social scene which only occasionally tempts Kim away from her duties to Misty.