More sci-fi adventures for the gallant Timelord and his faithful chums. This time around, the TARDIS malfunctions and shrinks the Doctor (William Hartnell) so that he is just one inch tall. He then arrives on Earth and uncovers a diabolical plot by a ruthless businessman who has developed an insecticide so powerful that it will wipe out all insect life on the planet. The Doctor and his companions Barbara (Jacqueline Hill), Ian (William Russell) and Susan (Carole Ann Ford) try to put an end to these foul schemes, but that's obviously not so easy when you're no bigger than a thimble.