Serial 4H:
Planet Of Evil

Starring: Tom Baker (The Fourth Doctor), Elisabeth Sladen (Sarah Jane Smith). 

The Doctor and Sarah land on Zeta Minor, at the very edge of the universe. A scientific team led by Professor Sorenson is being terrified by an anti-matter monster, a situation which deteriorates when Sorenson takes a sample of anti-matter off-planet. The Doctor must stop Sorenson,
who has begun mutating into a Jekyll-and-Hyde-like anti-man, and restore the balance on Zeta Minor before death comes calling for them all.

Planet Of Evil was one of seve
ral Doctor Who stories directly inspired by script editor Robert Holmes' love of gothic fiction -- in this case, Robert Louis Stevenson's The Strange Case Of Dr Jekyll And Mr Hyde. Holmes contacted a colleague of his, Louis Marks, about penning such an adventure; Marks had himself written two previous Doctor Who serials, most recently Day Of The Daleks in 1972. Holmes also suggested Marks draw inspiration from the 1956 science-fiction film Forbidden Planet, which featured a monster arising from a scientist's id attacking the crew of a spaceship.

Marks took these ideas and added to them an anti-matter t
heme which ultimately became predominant. The final result was a four-part story entitled Planet Of Evil. Because it was felt that the "anti-matter monster" of the serial was very similar to the "id monster" of Forbidden Planet, it was decided to set Planet Of Evil in a jungle environment, to contrast with the desolate setting of the movie. To this end, and because no location filming was allocated for Serial 4H, designer Roger Murray-Leach designed a fabulously detailed, exotic and alien jungle set. This proved so successful that it was extensively photographed by the BBC Educational Service, which would use it as an example of excellent set design for years afterward.

However, the jungle set did cause some problems. Loc
ating sound booms was virtually impossible, and this forced most of the dialogue to be re-recorded and dubbed in post-production. Furthermore, when it came to the visual effect of the anti-matter monster moving through the jungle, it was very difficult to achieve the appearance of the monster behind objects. Instead, because a Colour Separation Overlay mask had to be positioned in the shot, the monster was usually in the foreground.

Despite these hurdles, production on these segment
s went smoothly under director David Maloney; Maloney had just completed work on Genesis Of The Daleks at the start of 1975. The jungle set was erected at Ealing and filming occurred in mid-June. Cast and crew then returned for the studio material beginning on June 30th. Although Planet Of Evil was the second serial to be made as part of the thirteenth recording block and the second to be aired in Season Thirteen, it was actually broadcast before the story made before it, Pyramids Of Mars. Terror Of The Zygons had been held over from the previous production block to start off the season, and the order of the next two serials had been transposed to achieve a better balance of alien/Earth and studio/location stories.