This poignant novel, on the surface, appears to deal with loss. The horrific events of 9/11 seem to represent little in the way of hope or second chances. However, upon examination, the proverbial silver lining emerges in presenting some second chances for the characters.
Mr. A. R. Black is a reclusive older gentleman who lives in Oskar's building. He begins to help Oskar with his search for the symbolic lock which will help Oskar begin to reconnect with his dead father. For Mr. A. R. Black, this journey is his second chance to reconnect with other people and with the world in general.
Mr. William Black is the husband of a woman whom Oskar first contacts on his quest to find the lock for the key. The key actually fits a safe deposit box rented by William Black's father, who had died leaving him a letter about the key and box that William opened only after he had sold the vase containing the key to Oskar's father. This key provides William the chance to discover the final message his father left for him and a second chance to reconcile his feelings about his father.
Oskar's mother understood the intensely close relationship between Oskar and Tom, her husband. While feeling little jealousy about the relationship while Tom was alive, she seems at a loss to communicate with her son effectively after Tom's death. Her secret perserverence in following her son's progress on his journey eventually results in a connection between them that had not existed before. Thus, Oskar's mother has a second chance to bond with her son.
Finally Oskar himself has a second chance to reconcile his grief and to move on from his secrets. He no longer feels the need to harm himself physically, and, even though the key was never meant for him, it did provide him with an important step in his grieving process, leaving hope that Oskar will emerge from the tragedy intact.