I could not have what I wanted most. Mr. Harvey dead and me living. Heaven wasn't perfect. (2.39)
The ending is about as happy as a book about a murdered girl can get. It features the fulfillment of one of Susie's utmost desires, articulated in Chapter 2 (and in the quote up top). Mr. Harvey is interrupted from pursuing his latest teen victim, and plummeted to his death by, of all things, a falling icicle. Said icicle might or might not have been dislodged by Susie's ghostly interference. We like to think she had a hand in things. Notice also that Harvey's death by icicle is cleverly foreshadowed at a midpoint in the novel. Susie tells us:
In heaven, "How to Commit the Perfect Murder" was an old game. I always chose the icicle: the weapon melts away. (10.139)
Ahh yes, revenge is sweet, but Susie's desire for Mr. Harvey's death is based more in preventing him from hurting others than revenge for its own sake. Even though she's already in "wide wide Heaven" (see "Setting" for more), she can only truly stop her Earth-angst if she doesn't have to worry about this creep hurting people. Mr. Harvey's death begs a question: Where does he go when he dies? What do you think?
Creepy ponderings aside, that tragically happy aspect of the ending is followed by the next best thing to the restoration of Susie's life on Earth: the birth of her niece and namesake, baby Abigail Suzanne, the baby of super-couple Lindsey and Samuel. The birth gives the novel a sense of formal unity. A novel that begins with the death of a young girl, ends with the birth of another. She won't replace Susie, of course, but she can help Susie's loved ones heal.