Thorby is a young, defiant boy who is purchased at a slave auction on the planet Jubbul by an old beggar, Baslim the Cripple, for a trivial sum and taken to the beggar's surprisingly well-furnished underground home. Thereafter, Baslim treats the boy as a son, teaching him not only the trade of begging, but also mathematics, history, and several languages, while sending Thorby on errands all over the city. Thorby slowly realizes that his foster father is not a simple beggar, but is gathering intelligence, particularly on the slave trade. In addition, Baslim has Thorby memorize a contingency plan and a message to deliver to one of five starship captains in the event of Baslim's arrest or death. When Baslim commits suicide to avoid being captured alive by the local authorities, Thorby delivers the message to Captain Krausa of the starship "Sisu". Because the "Free Traders", to whom Krausa belongs, owe a debt to Baslim for the rescue of one of their crews from a slaver, the captain takes Thorby aboard at great risk to himself and his clan.