The mountain lion (A Zia book)

Eight-year-old Molly and her ten-year-old brother Ralph are inseparable, in league with each other against the stodgy and stupid routines of school and daily life; against their prim mother and prissy older sisters; against the world of authority and perhaps the world itself. One summer they are sent from the genteel Los Angeles suburb that is their home to backcountry Colorado, where their uncle Claude has a ranch. There the children encounter an enchanting new world—savage, direct, beautiful, untamed—to which, over the next few years, they will return regularly, enjoying a delicious double life. And yet at the same time this other sphere, about which they are both so passionate, threatens to come between their passionate attachment to each other. Molly dreams of growing up to be a writer, yet clings ever more  fiercely to the special world of childhood. Ralph for his part feels the growing challenge, and appeal, of impending manhood. Youth and innocence are hurtling toward a devastating end.