->''"Do you know why I'm a success, Mr Farrow? Because I've never allowed the word "can't" to exist."''
Given a second series [[note]](though this story and the next were actually filmed as part of the first series)[[/note]], ''Series/DoctorWho'' kicks off with a sci-fi staple — [[IncredibleShrinkingMan the heroes are shrunk to about an inch tall]].
All the usual fun and frolics with perfectly normal household objects becoming perilous deathtraps are there, but they also uncover a plot by a ruthless businessman Forester to launch a new insecticide, [=DN6=], despite it being harmful to other life. A civil servant investigates, but is murdered by the businessman (told you he was ruthless).
Barbara is made ill by the insecticide, but the others manage to foil the plan by tampering with his telephone, causing the local telephone exchange operator to be suspicious and send her policeman husband along to investigate. He isn't murdered, and brings Forester to justice.
The Irwin Allen series LandOfTheGiants bears a remarkable similarity.
[[http://www.dailymotion.com/playlist/x1k0rh_matrixarchive_planet-of-giants Watch it here.]]
!!This story provides examples of:
* HandWave: The reason behind the shrinkage of the Doctor and Co. is...Space Pressure.
* LittleOldLadyInvestigates: Hilda.
* MissingEpisode: A near-unique example for the series; "Planet Of Giants" was originally recorded as four episodes, but later the third and fourth were combined into a faster-paced Episode 3 (the unused footage was destroyed). This ended up leaving a one-episode hole at the very end of the Season 2 production block, which was filled by "[[Recap/DoctorWhoS3E2MissionToTheUnknown Mission to the Unknown]]". The DVD has a reconstruction of the missing scenes, using Carole Ann Ford, William Russell, and soundalikes for the dead cast members.
* MyGodWhatHaveIDone: Smithers when he realises just how dangerous his pesticide is, especially after his cat dies.
* ObstructiveBureaucrat: Subverted: Forester thinks of Farell this way, but he's actually in the right.
* PoorCommunicationKills: Barbara gets poisoned and gets progressively more ill as the show goes on, but hides it because... why?
** CannotSpitItOut: A lot of people seem to think this is a plot hole, but it's really just traditional British culture. Everybody's already trying to get back to the TARDIS, so explaining the poisoning would just hurt them unnecessarily.
* PyroManiac: The Doctor seems ''very'' enthusiastic about causing a gas explosion.
* SmartBall: Susan with her observations about the nature of the insecticide. May simply be her failing to hold the IdiotBall for once, given her [[InformedAttribute Informed intelligence]] in the pilot and a few episodes.
* TwoScenesOneDialogue: When they finally realize that no, they're not at the World Fair.
* WellIntentionedExtremist: Smithers believes initially that his pesticide is the only way to avoid world starvation.
* YankTheDogsChain: the uncontrollable [=TARDIS=] lands by chance back on Earth in Ian and Barbara's home period, but they're three inches tall and have no way of getting back to normal without taking off and getting lost again.