After Mellium,daughter of the Guardian Commander shows them the multi generational statue built over time during their journey to honor their ancestors and descendants, her father falls ill and the doctor and his companions are suddenly prime suspects by Guardian head of security Zentos. Since the cold was cured on Earth millennia ago,Dodo's is more virulent to their society. After Steven volunteers himself as a representative for the trial,he too falls ill and the Guardian Commander orders from his own sick bed that Steven be used as a guinea pig for the doctor-who did claim responsibility for the illness,to help find a cure. Using fluid from every animal,the doctor is able to synthesize the original vaccine for the common cold-curing Steven and the Guardians as well. After Zentos,the Commander,his daughter Mellium and attorney Baccu thank them and bid them farewell. Upon leaving in the TARDIS the doctor and his companions find themselves in the same place-only to find the statue has been completed to resemble a Monoid.
They find that shortly before arriving on Refusis III,the virus that had once nearly killed the humans had weakened many of them-to the point where the put upon Monoids were able to force them into building vocal translators for them so that the Monoids could stage a revolution against the humans,reduced themselves now to a labor class,allowing the Monoids alone to colonize Refusis III for their own new life. And the Monoids reveal that they have planted a nuclear bomb to destroy the humans on the Ark upon their departing Upon journeying to the surface of the planet in one of the Ark's colony ships while Steven stays behind to help locate the bomb,the doctor discovers an entire empty humanoid city-populated by no one but the non corporeal Refusians,who built the facilities for the humans they now welcomed-if only they would use the planet in peace. After pointing out to the Monoid Leader Four the error of his ways,he turns against his fellow treacherous monoids and reveals the location of the bomb inside the Moinoid statue,which is ejected from the Ark in time when the Refusians offer both humans and Monoid to colonize their world if only,that is they are willing to live in peace as equals.
This is a fantastic Doctor Who story and one of my personal favorites in the programs earlier history. For her short time and use of Mod catch phrases such as "gear" and "fab",much to the doctors irritation proves herself a well adjusted and helpful companion-using good sense thinking to get herself,Steven and even the doctor out of sticky situations. She learns quickly and tends to see the glass as half full in life. The story itself is an excellent treatise on unspoken slavery. Though touting themselves as enlightened and peaceful,the Guardians at the beginning of their journey hardly even notice the subservient position they have put the Monoids into. That is,of course it isn't too late. While the exploited Monoids nearly end up becoming the exploiters themselves, it is not the doctor but the very enlightened Refusians,using their guise of non corporeality as a cover,who help both human being and Monoid to see the era of their ways. The writing is sharp,the dialog is involving and the story is extremely well paced. Even the special effects are surprisingly effective. An excellent story,one of only two full surviving featuring Dodo Chaplet and highly recommended to all Whovians who have not yet seen it.