Moose Flanagan and his family have just moved to Alcatraz Island so that his father can take a job as a prison guard and his sister Natalie can go to a special school in San Francisco. Moose misses his old baseball team, and he struggles for recognition in his new school.
Then his sister Natalie, who suffers from autism, is rejected from the Esther P. Marinoff School, crushing his parents' hopes for Natalie's education. Now Moose must take care of Natalie after school while his mother teaches music lessons, and he must find a way to deal with Natalie's screaming fits and constant needs. Complicating Moose's life even more is Piper, the daughter of the prison warden. Piper lures Moose into her scheme to make money by collecting laundry from their classmates with the promise that Al Capone is among the convicts assigned to laundry duty on Alcatraz.
Gradually Moose adjusts to life on Alcatraz, even finding ways to help Natalie fit in with the other children on the island, and he is able to convince his mother that he really does have his sister's best interests in mind. After the Flanagans have tried repeatedly and unsuccessfully to enroll Natalie in the Esther P. Marinoff School, Moose secretly writes a note to Al Capone, asking him to help Natalie. Piper slips Moose's note into the prison's dirty laundry, and a few weeks later, Natalie is accepted to a brand-new school for older autistic children, to the delight of the entire Flanagan family.
Gennifer Choldenko was born in Santa Monica, California, in 1957, the youngest child in a family of four children. One of Choldenko's sisters suffered from severe autism and inspired the character of Natalie in this book. Choldenko began her writing career with a job as a copywriter in a small ad agency. She began taking classes in illustration, and this eventually led to a full-time study of illustration at the Rhode Island School of Design. After becoming very successful in advertising, she began to pursue her real love children's books, and her first novel Notes from a Liar and Her Dog was chosen as a School Library Journal Best Book of the Year and won several other awards. Choldenko is married with two children, and she lives in the San Francisco Bay area.