Winnie Perry is finally a teenager! In her thirteenth year, she discovers just how complicated life can be. She feels stuck between her friends, as Cinnamon is growing up too fast and Dinah is growing up to slow. Family relationships are becoming more complicated, too, as her sister is in her senior-year of high-school, and her brother is complaining about the first-grade. Winnie’s parents have a BIG surprise: They’re having a baby.
As in the last two novels in the series (Eleven and Twelve), events are told by months of the year, and the year starts on March. The book opens up on Winnie’s birthday, and it ends with the birth of Winnie’s new sibling (I won’t spill the gender), a few days before Winnie’s fourteenth birthday. With Winnie’s sister Sandra going off to college, Winnie knows she’ll have to be a big sister to Baby Perry. She’s up for the challenge.
Throughout her year, Winnie changes and grows in many ways, but still remains the same likable girl that she was in Eleven.