Doc delivers a parcel and terraforming turns humanoids into Better-Zarbis, but then it turns out they were destined for greater things all along.
The Third Doctor and his companion Jo Grant receive an assignment from the Time Lords, as they have now become their personal, intergalactic DHL. Together, they go to the planet of Solos in the 30th century. The human empire is preparing to grant independence to Solos, but the local Marshal objects and stages a coup.
His plans include terraforming Solos to accommodate human life with complete disregard to the Solonians who would perish in the process. Coincidentally, said Solonians are undergoing a metamorphosis of sorts, though, and are turning into giant Gregor Samsas, and thus the plot thickens.
Will the Doctor be coerced into doing the humans’ bidding? Will he deliver his package and bone out of there? Will he help the warrior Solonians, join the mutant Solonians or aid them all in achieving the godlike status that they are apparently destined for?