|Doctor Who-The Mutants|
Meanwhile there is a problem. Solos,with an atmosphere polluted by human settlers that natives can survive in but humans cannot is believed to have caused a plague in which natives are mutating into hostile,bipedal Scorpion-like creatures. With Jo,Ky and even some of the disaffected personal of Sky Base being consistently held prisoner by Marshal for resisting his single minded mission Jo and Ky escape to the surface of Solos where,temporarily separated from Ky,Jo finds herself in an unusual glowing cave,and before fainting encounters a figure in some type of special suit. Upon the doctors reuniting with Ky and another confrontation with the Mutts,the local name for the Mutants they inspect the box only Ky can open. Inside are stone tablets with writing that Ky reveals would only be understood by a human teacher named Sondergaard,thought long missing.
It isn't long before they meet up with Sondergaard however. Already aware that Marshal's reasons for declaring Marshall law on Solos is due to the presence of Thaesium,an important power source that would have great value for humanity. Sondergaard has come to understand the Thaesium is the source of mutations around him,but still unaware in what capacity. Upon studying the stone tablets gifted to Ky from the time lords the doctor and Sondergaard discover they are ancient local glyphs symobolizing the planets 2,000 year orbit around it's sun,and that each season of Solos is 500 years long. This leads the conclusion that these are not in fact mutations occurring but a natural stage of an evolutionary change in the Solarians that has been delayed by Jaeger and Marshal's experiments with the atmosphere.
Upon escaping from Marshal yet again,Jo is able to contact a space shuttle containing Earth leaders. They arrive in time to hold a trail where Marshall actions are subject to scrutiny Sondergaard,who remained on Solos to try to bring the mutant Solarians to the council as proof presents them during this time. Meanwhile the doctor has discovered a crystal in this Thaesium gave that he researches and discovers it's a key regenerative favor in the Solarians evolutionary process. He gets it to Jo and Ky before they are again imprisoned. The combination of the crystal and the high Thaesium radiation dosages result in Ky undergoing the full evolutionary change into a nearly Omnipotent humanoid being who enevitably defeats and kills Marshall and frees the Earth council whom he'd held captive. Sondergaard agrees to stay on Skybase to help undo the damage done on Solos before the doctor and Jo depart.
This serial is one of the most complex and provocative episodes of the third doctor era. In addition to exploring the political improprieties of imperialism that Doctor Who was already well acquainted with,it also explored though in brief the inherent racism involving maintaining such a system. The "outworlder" humans and the Solarians were depicted as using "separate but equal" segregated facilities. There's also an implication that Marshal had a better idea of the Solarian's evolutionary process than he led on,and feared it because it would spell the instant independence of the race from his falling and bloated empire. Throughout the serial too you notice that while Jo Grant,as is often the case spends most of the serial imprisoned in some fashion or other has learned to become very Wiley,and more than capable of getting out of trouble without the help of the doctor. This was an important step in the growth of her character. And this intricately written serial was in many ways an excellent way to express this point too.