With the newly regenerated Doctor behaving violently, Brigadier Lethbridge-Stewart and UNIT have to contend with the theft of the plans for the new disintegrator gun by what seems to be a mechanical monster. The theft is the beginning of a plot to hold the world to nuclear ransom. The culprits are certain members of staff who work at the Scientific Reform Society who have stolen the beast and taught it to kill. This Doctor Who episode aired in 1974/1975.
Part 1
Section 1.1
Section 1.2
Section 1.3
Part 2
Section 2.1
Section 2.2
Section 2.3
Part 3
Section 3.1
Section 3.2
Section 3.3
Part 4
Section 4.1
Missing, unfortunately.
