Davey Wexler, along with her mother, Gwen, and her little brother, Jason, has just attended the funeral of her father, Adam, who was shot to death in a holdup at their 7-Eleven convenience store in Atlantic City. After lying in bed for days on end and not eating, she starts her tenth year of school, but ends up passing out three days in a row.
Davey's mother, Gwen, then decides they needed to get away for a couple of weeks, so they take up an offer from Adam's older sister, Bitsy, and her husband Walter, to come stay with them in Los Alamos, New Mexico. However, a few days before they were scheduled to leave, Gwen gets news that their store was further vandalized, and she decides they're going to stay longer. It turns out to be pretty much the entire school year.
While there, Bitsy and Walter, who do not have children and were never able to have them, start treating Davey and Jason like their own, which eventually creates tension between Davey and the both of them when they won't let her do a number of things out of fear of her getting hurt or killed, and more so when her mother just sits back and allows it to happen. During this time, she gets a job at the Los Alamos National Laboratory as a temporary. She also sees a therapist named Miriam and convinces Davey to see her as well.
Meanwhile, as Davey explores the town on her aunt's bicycle, she goes to a canyon and after climbing down she runs into an older boy who calls himself Wolf. Davey calls herself Tiger when they introduce each other. She also becomes a candy striper at the hospital with her new friend, Jane, and meets a cancer patient who turns out to be the father of Wolf. The inspiration from Wolf and his father changes Davey for the better.
Another story is Jane's alcoholism and Davey's desire to help her get out of it. Also, in three different parts Davey describes the evening her father was shot and killed, which causes her in at least one part of the book to completely freak out when Jason experiences a nosebleed from the altitude. She carries a paper bag with her, which is revealed to contain the clothing she was wearing when she found her father and cradled him all the way to his death. The clothing was soaked with his blood. After a session with Miriam, where she finally breaks down and is able to mourn her father, she eventually buries it and a bread knife she was carrying for self-defense in a cave in the canyon she met Wolf in.
Eventually, against Bitsy's wishes, Gwen decides to return the family to Atlantic City to begin a new life, so Walter helps them buy a car for the trip home. Gwen gets a job in one of the hotels, thanks to the credentials she gained while working at the lab, and with the aid of her friend, Audrey. Once they're back home, Davey often wonders if anyone will know how much she had changed, particularly her friend, Lenaya, and her boyfriend, Hugh, then also has the realization that some changes happen deep down and only you know about them.