The Sensorites

The TARDIS materialises on board a 28th century Earth spacecraft orbiting the sense-sphere. The Sensorites, inhabitants of the sense-sphere, have trapped the ship's crew, Captain Maitland, Carol, and John, in a state of semi-paralysis. The Sensorites also steal the locking mechanism from the TARDIS, trapping the Doctor and his companions.

The Sensorites, through a telepathic link with Susan, allow all but Maitland and Barbara to travel to the surface, where Ian falls ill from a deadly disease that has been killing the Sensorites.

The Sensorites tell the Doctor that they know the humans have found the mineral molybdenum on the planet, and are wary of being exploited. They are wary of the humans as many Sensorites have died since a previous expedition left the planet.

The Doctor discovers that three humans from the first expedition have been adding deadly nightshade to the water supply. Captain Maitland promises oo not disclose the existance of the Sensorites.

• Captain Maitland: Lorne Cossette;
• Carol Richmond: Ilona Rodgers;
• John: Stephen Dartnell;
• First Elder: Eric Francis;
• Second Elder: Bartlett Mullins;
• City Administrator: Peter Glaze;
• Sensorites: Ken Tyllsen, Joe Grieg;
• Commander: John Bailey;
• Survivors: Martyn Huntley, Giles Phibbs;