When a Nestene Energy Unit is stolen and a radio telescope sabotaged, the Doctor is contacted by a Time Lord who tells him his old rival the Master is responsible.

Attempting to find out where Jo encountered the Master, the Doctor heads to the circus where he falls foul of Rossini.

The Doctor and the Brigadier head to Farrel's factory but the Master and the Autons have already left and are distributing plastic daffodils around the country.

The Doctor discovers the plastic daffodils are designed to fire a spray that asphyxiates people, causing havoc prior to the Nestene's arrival, but before he can alert anyone he and Jo are captured by the Master.