When the story opens an adolescent boy named Thorby is being sold on the slaver’s block in the ironically named Plaza of Liberty in Jubbulpore, the capital of Jubbul, which is itself the capital of the Nine Worlds ruled by the Sargon. The Nine Worlds is presented as an oriental despotic empire complete with a caste system that includes slaves, beggars and thieves as acknowledged roles in the society. Now this is embedded in a future that includes interstellar space ships, faster than light communication and a human civilization that has spread hundreds of light years from Earth.
Baslim the crippled beggar manages to purchase the boy. He overcomes the boy’s ferocious hatred of his owners and uses kindness and fatherly discipline to raise the boy to be an honest and resourceful man. As time goes on Thorby figures out that Baslim is a lot more than just a beggar. Inside his lodgings in the underground slums of Jubbulpore, Baslim has modern teaching equipment that he uses to teach Thorby languages and mathematics and the history of the world he lives in. Also, Baslim seems to be a spy, collecting information on the slave trade on Jubbul. Eventually Baslim tells Thorby that someday Baslim would be gone and Thorby must leave Jubbul to escape from the squalor and injustice that was life in the Nine Worlds. He uses hypnotic suggestion to implant a message in Thorby, that when delivered by the boy, would tell one of Baslim’s friends, who was a starship captain, that rescuing the boy would be the payment for a favor Baslim had done for the captain’s family.
And one day Thorby finds that Baslim has been arrested and executed as a spy and that the Sargon’s men are after Thorby. Luckily Thorby had spotted Captain Krausa of the starship Sisu. The message and the implied debt are acknowledged the Captain and by clever subterfuges performed by Thorby’s friends he is smuggled aboard the Sisu and escapes Jubbul.
Overcoming his grief at the death of his adoptive father Baslim, Thorby is adopted into the family that is the crew of Sisu. A complex phratry and moiety arrangement connects the “family” on Sisu with the other Trader ships with their own “families.” Thorby struggles to adapt to the strange ways of his new family but the connection to his ship mates stabilizes the boy and gives him the sense of belonging he needs.
But what Thorby doesn’t know is that Baslim had told Captain Krausa that Thorby probably had a family somewhere out in the free worlds beyond the Nine Worlds. Krausa was committed to hand Thorby over to the authorities of the Space Guard, when he could, for reunion with his family. But Thorby’s relation to Baslim means that the Sisu would gain great status with the other Trading families by keeping Thorby in their family.
After many adventures including shooting a space pirate ship out of the skies Thorby is finally returned to the Space Guard. He learns that Baslim was a highly decorated officer in the Guard and he was doing espionage to help destroy the slave trade. For someone associated with Baslim the Guard does everything humanly possible to help Thorby and finally finds his true family. The details of this final chapter take him back to Earth and solves the mystery of his years as a slave.
Heinlein has crafted a story that combines facets of adventure stories from many sources. Others have noted that there are some elements of the story that are reminiscent of Kipling’s novel Kim. But mostly it contains the elements of Heinlein’s Future History Universe. I especially found the world of the trader ship Sisu very imaginative and enjoyable. But the whole book keeps the reader engaged, the characters are excellently drawn and the plot is lively. Once again this is a Heinlein juvenile that is highly recommended.