Content Warning: This section of the guide represents ableist attitudes and language present in the source text, which are replicated in direct quotes only.

Twelve-year-old Moose Flanagan lives on the bleak prison island of Alcatraz, where the mobster Al Capone and 277 other hardened convicts are serving time. His father, Cam Flanagan, brought the family to Alcatraz seven months earlier, in January 1935, to work as a prison guard and electrician. Moose, his parents, and his 16-year-old sister Natalie share a small apartment in Building 64, the island’s civilian quarters. They sometimes have their plumbing repaired by the convict Seven Fingers, an axe murderer.

The prisoners perform many other services on the island: Al Capone and the notorious Machine Gun Kelly are among the cons who do the island’s laundry. Other, unpopular guards, such as the brutish Darby Trixle, sometimes get their clothes back vandalized, but Capone seems to have a soft spot for the Flanagans: Moose even believes that the mobster pulled strings on his behalf to help get his sister Natalie, who has autism, into a special boarding school in the city, the Esther P. Marinoff School.