Well, this woman in the canoe belonged to a tribe which had been at war with the king of Fantippo—an African kingdom situated on the coast near which the swallows had seen the canoe.
And in this war the King of Fantippo had taken many prisoners, among whom was the woman's husband. Shortly after the war was over some white men in a ship had called at the Kingdom of Fantippo to see if they could buy slaves for tobacco plantations. And when the king heard how much money they were willing to give for black slaves he thought he would sell them the prisoners he had taken in the war.
This woman's name was Zuzana and her husband was a very strong and fine-looking man. The King of Fantippo would have kept Zuzana's husband for this reason, because he liked to have strong men at his court. But the slave traders also wanted strong men, for they could do a lot of work on the plantations. And they offered the King of Fantippo a specially high price for Zuzana's husband. And the king had sold him.
Zuzana described to the Doctor how she had followed the white man's ship a long way out in a canoe, imploring them to give her back her husband. But they had only laughed at her and gone on their way. And their ship had soon passed out of sight.
That was why, she said, she hated all white men and had not wanted to speak to the Doctor when he had hailed her canoe.
The Doctor was dreadfully angry when he had heard the story. And he asked Zuzana how long ago was it that the slaver's ship bearing her husband had left.
She told him it was half an hour ago. Without her husband, she said, life meant nothing to her, and when the ship had passed from view, going northward along the coast, she had burst into tears and just let the canoe drift, not even having the heart to paddle back to land.
The Doctor told the woman that no matter what it cost he was going to help her. And he was all for speeding up his ship and going in chase of the slave boat right away. But Dab-Dab the duck warned him that his boat was very slow and that its sails could be easily seen by the slavers, who would never allow it to come near them.
So the Doctor put down his anchor and, leaving the ship where it was, got into the woman's canoe. Then, calling to the swallows to help him as guides, he set off northward along the coast, looking into all the bays and behind all the islands for the slave ship which had taken Zuzana's husband.