Robert Heinlein's Citizen of the Galaxy #2

Just outside our galaxy the atrocities of slavery thrive, and young Thorby is just another orphaned boy sold at auction. But when he crosses paths with a mysterious crippled beggar his destiny is forever changed. And now as his knowledge and skills mature Thorby becomes increasingly aware of how his ever-changing fortunes could affect the destinies of us all. Citizen of the Galaxy is an interstellar action/adventure, coming of age tale by the 'Dean of Science Fiction', Robert A. Heinlein!