After an abortive holiday in Brighton, Romana persuades the Doctor to take another on the planet Argolis which in the year 2290 is the location of a giant pleasure dome, the leisure hive.

The Argolins are dying. The radiation on their planet's surface, the result of a war with their enemies the Foamasi, has rendered them sterile. Pangol, the youngest Argolin alive, was actually created by the Tachyon Recreation Generator, a machine used to generate games in the hive. He now secretly plans to re-create himself many times over, forming an army of duplicates to destroy the Foamasi for good.

The Hive's leader, Mena (Pangol's mother), is being persuaded by her Earth agent Brock to sell the Hive to the Foamasi who have made a good offer, but Pangol vehemently opposes this plan. As Mena grows weaker, Pangol takes command and attempts to create his army. However, the Doctor has tampered with the equipment and an army of Doctors emerges instead. The duplicates are also unstable and quickly vanish.

The hive turns out to have been infiltrated by some Foamasi agents from their planet's government, who expose Brock and his assistant, Klout, as being renegade Foamasi members of the West Lodge. Mena and Pangol enter the TRG following the Doctor's tampering and are rejuvenated - Mena into a young woman and Pangol a mere babe in arms.

_{Synopsis from Doctor Who: The Fourth Doctor Handbook by David J. Howe, Mark Stammers and Stephen James Walker, reprinted with permission; further reproduction is not permitted. Available from Telos}