A newly regenerated Doctor is led into a trap-within-a-trap-within-a-trap when his arch-enemy the Master, uses the mathematical abilities of the Doctor's travelling companion Adric to create Castrovalva; a town whose dimensions fold in on itself.

The Doctor is compelled to repair the Chameleon Circuit which has affected the exterior look of the TARDIS for a long time. Along the way the Doctor discovers that the Master is alive and was able to escape Traken! Can the Doctor prevent the Master from unravelling the entire causal nexus of the Universe?

Trouble is brewing once again; a series of robberies are taking place which seem linked to plans for a top secret disintegrator gun. All evidence seems to point to the culprit being a sentient robot, created by an eccentric professor and owned by a think tank. However, the robot's basic programming prevents him from killing, providing a contradiction to the clues. At the same time, the Doctor is recovering from his latest regeneration; can he regain his senses and help UNIT solve the case before time runs out?

The blue crystal that the Doctor took from Metebelis 3 in a previous adventure (The Green Death) is desperately sought by the Eight Legs, a race of mutated spiders, as the final element in their plan for universal domination. With help from an old mentor, the Doctor realizes the only way to foil the plot is to make the ultimate sacrifice. The Doctor must risk death to return to the cave of the Great One and save the universe.

The new Doctor soon joins forces with his old friend the Brigadier along with UNIT, and with the recently recruited Dr Elizabeth Shaw, but time is running out. Irregular things are happening at a nearby plastics factory, while faceless creatures lurk in the woods. The Nestenes have landed a spearhead force and plan to conquer the country by substituting plastic Auton replicas for men and women in key government and military posts.

The Doctor, Jamie and Zoe arrive on an unnamed planet. At first believing themselves to be in the midst of World War I, they realize it is one of many War Zones overseen by the War Lords, who have kidnapped large numbers of human soldiers. Infiltrating the control base, the Doctor discovers that the War Chief is also a member of his own race. The creeping realization sets in that the Doctor cannot solve this problem alone, and that his days of wandering may be at an end...

The Doctor, Jamie and Zoe arrive on an unnamed planet. At first believing themselves to be in the midst of World War I, they realize it is one of many War Zones overseen by the War Lords, who have kidnapped large numbers of human soldiers. Infiltrating the control base, the Doctor discovers that the War Chief is also a member of his own race. The creeping realization sets in that the Doctor cannot solve this problem alone, and that his days of wandering may be at an end...

The Doctor, Jamie and Zoe arrive on an unnamed planet. At first believing themselves to be in the midst of World War I, they realize it is one of many War Zones overseen by the War Lords, who have kidnapped large numbers of human soldiers. Infiltrating the control base, the Doctor discovers that the War Chief is also a member of his own race. The creeping realization sets in that the Doctor cannot solve this problem alone, and that his days of wandering may be at an end...

This is the fulcrum of the entire series folks! The make or break story that had the entire franchise on the line. Will the fans accept a new Doctor played by Patrick Troughton??

Welcome to another feedback episode folks! In this one we cover some questions and feedback from our look at The Tenth Planet in the previous episode