The Master took control of Rex and used his factory to manufacture Autons and other Nestene-controlled plastic products for the upcoming invasion. These included: a plastic chair that smothered Farrel Plastics' production manager McDermott; a plastic troll doll that killed John Farrel; a telephone cord that almost strangled the Third Doctor; and plastic daffodils that — when activated by shortwave radio signals — sprayed an airtight plastic mask over a victim's face, suffocating them.
Jo Grant was assigned to investigate the factory to see if their was anything suspicious. She was found by the Master and hypnotised. She forgot everything she had heard and seen and returned to UNIT. She had also been hypnotised so that when she returned to UNIT, she would blow it up with a bomb.
The Doctor discovered the Master's plan and — after pointing out that the Nestenes would be unlikely to allow the Master to rule Earth alongside them — convinced the Master to work with him to stop the Nestene invasion, while UNIT recalled the daffodils that had been freely distributed by the Autons. (TV: Terror of the Autons)