Katy is almost twelve years old and she has everything. Wonderful parents, a smart, supportive older sister, great friends, and a beautiful extended family that includes grandma, grandpa, aunts, and uncles, who are sometimes annoying, and sometimes not, as in all families. When Katy's sister is diagnosed with a serious illness, the whole household is turned on its head, with doctor's tests, appointments, fears, doubts, and bad moods. Katy has to learn to cope with a sister who was hit by the "evil creature," as she calls the illness. At the same time, Katy, together with her friends, deals with the trials of youth—a disappointing first love, a class queen who is not very nice, and a first kiss.