At the beginning of the novel, Astrid Magnussen is a twelve-year-old girl living in Los Angeles, California. She and her mother, Ingrid Magnussen, a poet, live a solitary life with little outside influence. Astrid's father, Klaus Anders, left before Astrid was old enough to remember him. Astrid relies solely on Ingrid and has trouble fitting in at school. However, Ingrid is self-centered, cold-hearted and eccentric. She lives by a set of her own rules and shows little interest in Astrid, seeming to forget she has a daughter at all. As a result, Astrid fears abandonment above all else.
Ingrid begins dating a man named Barry Kolker. At first, Ingrid is disgusted by this "goatman", and finds him repulsive. Barry continues to pursue her romantically and Astrid watches her mother break every self-imposed rule as she becomes more involved with him. Eventually, it is revealed that he is cheating on her with younger women, leaving Ingrid shattered and enraged. Numerous attempts at reconciliation leave Ingrid more and more humiliated and culminate with her breaking into Barry's house and spreading a mixture of DMSO, an arthritis drug, and oleander sap all over the surfaces of Barry's home. The DMSO allows the oleander poison to be absorbed into skin. As a result, Barry dies and Ingrid is charged with his murder. Sentenced to life in prison, she promises her daughter that she will come back, but Astrid is sent to a series of foster homes.
The first foster family is that of Starr, a former stripper, and recovering drug addict and alcoholic. She has two children of her own, as well as two other foster children. Starr takes in foster children because her own children were in foster care at one time due to her addictions. Despite the fact that he is old enough to be her father (Astrid is fourteen by this time), Astrid has an affair with Starr's live-in boyfriend, Ray, also known as Uncle Ray to the other kids. As Ray becomes more and more uninterested in Starr, she relapses. One night, after a loud, drunken argument with Ray over his relationship with Astrid, Starr shoots Astrid with a .38. Astrid suffers some broken bones and stitches from the gunshots and is hospitalized for a few weeks, and begins abusing the prescription drug Demerol, which is given to her during her stay at the hospital.
Her next home is with the Turlocks. Ed and Marvel are the parents of two small children. In their home, Astrid becomes an unpaid babysitter. Astrid befriends the Turlocks' next-door neighbor, a beautiful African-American woman named Olivia Johnstone. Astrid admires Olivia's beauty, wealth and hedonistic lifestyle. Olivia is a prostitute by profession and is hated by the Turlock family for her profession and race. After befriending Olivia, Astrid begins using drugs and performs oral sex on a boy in a park in exchange for marijuana. Olivia teaches Astrid about all of the finer things in life. On her fifteenth birthday, Astrid goes for a walk and is bitten by a pack of dogs, leaving scars on her arms and face. During the winter break, Astrid is expelled from the Turlock household after getting drunk and falling asleep at Olivia's house one night.
Next, Astrid is sent to the home of a Hispanic woman named Amelia Ramos. Amelia is an interior designer, originally from Argentina, and lives in a large, elegant house in Hollywood. Amelia has a son who has contracted AIDS, and Latina foster girls, but the girls do not see him much. All of the girls in Amelia's household are treated the same in that they are fed dinner, but Amelia keeps a lock on her refrigerator so the girls starve in the mornings. Astrid starves to the point that she stops menstruating. She resorts to eating unfinished lunches from the garbage at school. Astrid eventually gets a new caseworker who finds her a new placement.
Astrid is taken in by a former actress named Claire Richards, and her husband, Ron. Claire does everything she can to ensure Astrid's comfort. For once, Astrid is doing well in school and pursuing art. Astrid continues corresponding with her mother in prison, but Astrid becomes increasingly bitter towards Ingrid. Claire suspects that Ron is having an affair, and Astrid watches their fights worsen as Ron makes constant trips away from home. After New Year's, Claire commits suicide by overdosing. By this point, Astrid is seventeen.
Astrid is then placed in MacLaren Children's Center (known as Mac), which is known as a final resort for foster kids without a placement. Astrid meets an artistic boy named Paul Trout, and they bond through the shared experience of living in foster care and through art.
Astrid's final home is with Russian immigrant Rena Grushenka. She intentionally chooses Rena over better prospective foster parents because she is devastated by Claire's death and does not want to become part of a nuclear family. Astrid is afraid it would be too easy to forget the pain she has gone through. At Rena's, she lives with two other teenage girls named Niki and Yvonne (who is pregnant when Astrid arrives). Astrid becomes very close friends with Niki and Yvonne. Despite the fact that he is more than twice her age, she also has a sexual relationship with Rena's boyfriend, Sergei. One day, after getting high on acid with Niki, Astrid begins to have memories of a woman named Annie.
Meanwhile, Ingrid has begun to build up a group of fans and admirers from prison, who all believe she is innocent. Ingrid and her lawyer begin to build a case to get Ingrid released from prison. However, their case depends on Astrid — if she testifies that Ingrid did not murder Barry, Ingrid will likely not be sentenced, but if she tells the truth, Ingrid could not win her case. Astrid realizes that she is in a position of power over her mother, and tells her that unless she answers some of her questions, she will testify against her. Astrid asks Ingrid about Barry, Klaus and then Annie. Ingrid is shattered to learn that Astrid remembers Annie at all, and reveals that Annie was a babysitter whom Ingrid left Astrid with for over a year, making Astrid realize why she fears abandonment from her mother. Astrid lets Ingrid know how damaged she is because of what Ingrid did to her. Astrid gives Ingrid a choice, to have her testify, or to have her return to the person her mother knew her as. Ingrid makes the choice not to ask Astrid to lie for her, and lets her go.
Two years later, Astrid is aged twenty and living with Paul in a run down flat in Berlin, Germany. Astrid spends her time buying suitcases and making them into individual art pieces representing her different foster homes, detailing the journey she has taken from her mother's imprisonment to her life with Rena. Paul shows Astrid a newspaper containing an article about Ingrid's release from prison after a new trial acquits her of killing Barry. Ingrid's lawyer successfully used a theory Astrid made in jest during the final visit with Ingrid, where Astrid said she could tell the court that Barry committed suicide and faked it to look like Ingrid killed him. Astrid realizes that if she returns to California to reunite with Ingrid, she must abandon Paul, leaving him much as she had herself been abandoned so many times before. She embraces her life, the past that has made her who she is, and even her mother.