It's the start of winter, and Patrick is beginning to feel crowded out of his own family. His father's friend, Linda, and her seven-year-old daughter, Claire, are coming for dinner again. By the time spring arrives, not only is Patrick's father planning to marry Linda, but she and Claire will be coming to live with them at the summer's end. That just won't do. So Patrick comes up with a big idea. He'll build a tree house where he can stretch out his arms and breathe. But wait. Will his father allow it? Where will he find the perfect tree? Who will give him a hand with the construction? And, most importantly, will his own tree house really be the hideaway he hopes for, especially from the irritating Claire? As the autumn season arrives, Patrick discovers some surprising answers to these questions - and learns a little about the meaning of family.