Arnold must choose between the certain reality of life with Lila and childhood fantasy when Helga returns to Hillwood after twelve years when her mother passes away. His heart and mind play tug of war with his life... who will be the victor?

Now in their teens, Helga is on the other side of things as she considers her years of dating Arnold, plus the notion that it did not necessarily have to end that way. Now that Arnold is living in New York, following his dreams, Helga misses him terribly. After an event causes her to break off from her family, Helga gets advice on how to keep Arnold in her life on her own terms.

Leaving the jungle of San Lorenzo behind, Arnold and Helga begin 6th grade at P.S. 118 as an official couple. However, in the future, documented by a series of letters from a teenaged Helga to Arnold, we learn that their middle school life is in the past and the couple are living on opposite sides of the country. What happened to make them separate, and when, or if, will it change?