Alca­traz Island in the 1930s isn’t the most nor­mal place to grow up, but it’s home for Moose Flana­gan, his autis­tic sis­ter, Natal­ie, and all the fam­i­lies of the guards. When Moose’s dad gets pro­mot­ed to Asso­ciate War­den, despite being an unlike­ly can­di­date, it’s a big deal. But the cons have a point sys­tem for tar­get­ing prison employ­ees, and his dad is now in seri­ous dan­ger. After a fire starts in the Flana­gan’s apart­ment, Natal­ie is blamed, and Moose bands with the oth­er kids to track down the pos­si­ble arson­ist. Then Moose gets a cryp­tic note from the noto­ri­ous Al Capone him­self. Is Capone try­ing to pro­tect Moose’s dad too? If Moose can’t fig­ure out what Capone’s note means, it may be too late.