The book cover represent Carrie and Nick leaving everything behind and giving their back to the struggles they faced. The skulls represents two aspects of the story, the first is the war Carrie and her brother faced along with the pains. Second, it represents the skull that shows up frequently in the story.
Second option
The book cover represent Carrie and Nick leaving everything behind and giving their back to the struggles and how they are going back to their normal life after every thing that happened. The lines appear as rain drops that indicates sadness and bombs at the same time.
