Magic Tree House
Junie B. Jones
You don't know me, but I know about you.... I can't make you live longer, I can't stop you from hurting. But I can give you one wish, as someone did for me.
It's been months since Dani Vanoy's older sister Cassie has been diagnosed as having a brain tumor. And now the treatments aren't helping. Dani is furious that she is powerless to help her sister, and she can't even convince her mother to take the girls on the trip to Florida that Cassie has always longed for.
Then Cassie receives an anonymous letter and check. Dani knows she can never make Cassie well, but against all odds she dares to make Cassie's dream come true.
From the Paperback edition.