It's been months since Dani Vanoy's older sister, Cassie, was diagnosed as having a brain tumor. And now the treatments aren't helping. Dani is furious that she is powerless to help her sister. She can't even convince their mother to take the girls on the trip to Florida Cassie has always longed for.

Then Cassie receives an anonymous letter offering her a single wish. Dani knows she can never make Cassie well, but she is determined to see Cassie's dream come true, with or without their mother's approval.