Captain Pausert is a well-intentioned but inexperienced merchant traveler from the planet Nikkeldepain, voyaging solo on the old pirate chaser "Venture". While on the planet Porlumma, the captain is moved by sympathy to purchase three young sisters – Maleen (about 14 years old), Goth (9 or 10), and the Leewit (5 or 6) – who had been enslaved while visiting another planet on a jaunt of their own. In getting clear of Porlumma, the "Venture" escapes pursuit when the girls desperately use what they call the Sheewash Drive, which enables far faster transit than is possible with primary or secondary space drives available either in or outside the Empire. The girls reveal that they are witches from the planet Karres, with klatha (psionic) powers. The girls’ powers, but especially the possibility of this incredibly fast drive, draw the unwelcome attention of planets and ships they pass. After taking the three sisters to their homeworld of Karres, the captain attempts to return to his home planet but is stunned when faced with a barrage of criminal charges, many relating to his encounter with the witches and his brief stay on the prohibited planet of Karres; in addition, the planetary government avidly want the suspected new space drive. Captain Pausert escapes the Nikkeldepain police and military with the help of the middle sister, Goth, who had stowed away on the ship.