During the summer in which this story takes place (in the late 1940's, I think), Marcy, her older sister and younger brother, and a neighbor at their lake house are passionate about pretending to be Potowatami, members of a Native American tribe that lived in Wisconsin. But -- while they were gone for the winter, a Boy Scout camp has been constructed on their former Happy Hunting Grounds. Inflamed, the four "natives" declare war on the Boy Scouts, with both funny and moving results.