A Timelord warns The Doctor that an old adversary of his has arrived on Earth - The Master. The Master is in league with the nestenes who are planning another invasion attempt. This time, as well as creating the Autons, they plan to kill half a million people with plastic daffodils that spray a suffocating plastic film over their victims faces. In the confusion, the Nestines will arrive and take over - unless The Doctor, joined by new assistant Jo Grant, can stop them.