It is 1845, and twelve-year-old Josh is in Point Puer, the boys division of the Port Arthur convict prison in Van Diemens Land (Tasmania). But he cannot remember committing any crime, or how he got to Point Puer. And why do they keep calling him Tom Parish? Then an act of spite by a bully plunges Josh into a series of adventures, and he and Sarah, his surprising and resourceful new friend, must unravel the clues to the mystery of his identity.