The Green Death - Episode 4

At last, the Brigadier gets his reinforcements, and lots of them! Sergeant Benton is back, as is Captain Yates, although Mike is actually working undercover in order to infiltrate Global Chemicals. It's an interesting change of pace to see a UNIT regular in a more espionage-oriented role, I like it. The Doctor dressing up as the milkman and the cleaning lady is a bit weird and silly, but I guess it works to get him into Global Chemicals. The shots of the masses of maggots are very impressive, as is the destruction of the mine. The cliffhanger revelation that the mysterious unseen "BOSS" is actually a computer isn't as much of a shock nowadays as it might have been back when this first aired.