|Doctor Who-The Mawdryn Undead|
At a boys school in England,a student named Turlough is on the wrong side of an automobile accident and is promised his life will be saved and he will be returned to the planet of the original orgin,by the Black Guardian if he kills the doctor. The doctor for his part is returning to Earth with Tegan following her final experience with the Mara. Instead they find themselves forced into materializing on a luxorious spaceship that almost crashed into the TARDIS. In the meantime,Turlough is shadowing the doctor at every turn which leads to the fifth doctor encountering his old friend Brigadier Lethbridge Stewart,now a math teacher at the boys school Turlough is attending,but the Brigadier for his part has no memory of the doctor. After refreshing that memory,the Brigadier having had a nervous breakdown six years before,he and the doctor return to his TARDIS to locate the missing Turlough.
Finding it difficult to deal with doing the Black Guardians bidding,his moves become so erratic that Tegan and Nyssa try to rescue a man they think is the doctor. By this time the doctor is realizing the source of the Brigadiers nervous breakdown: a temporal paradox creating by the meeting of himself sometime in the past,deduced from the fact the brigadier of 1983 remembers meeting Tegan. Attempting to travel back to 1983,Tegan and Nyssa return with the TARDIS to 1977 where they meet the Brigadier of that time and ask for his help,unwittingly setting events into motion. In the end it turns out the man they believe is the doctor is an alien named Mardryn,from a group of criminals who stole time lord regenerative technology to extend their lives. It leaves them in a zonbified state where they are immortal but carry a virus that nearly does the same to Tegan and Nyssa when they attempt to leave in the TARDIS with the real doctor. Having been asked by Mawdryn to give up his last remaining regenerations to end their eternal misery he is forced to do so to save his companions. Before that happens the Brigadier from 1977 meets his future self,not only ending the eternal life of Mawdryn's people and saving Tegan and Nyssa from their virus but also restoring both brigadier to normal. In the confusion of returning both brigadiers to their proper time streams,Turlough remains on the TARDIS and asks to join the doctor.
There key issue to this serial in every sense is the misappropriation of time itself. Lethbridge Stewart,with his well intentioned but highly regimented thought process doesn't allow himself from either the past or present to fully grasp the concept of the time paradox that he himself is on the verge of creating. The two Brigadiers engage in nurmous near encounters with each other until they do meet and the result encounter has the exact effect it shouldn't have had. Mawdryn and his people,for their part,paid the ultimate price for their survivalist attitudes by having a doomed eternal life of great agony. Solid proof that the lack of understanding of one's greatest wish could very well be one's greatest undoing. As with many of the best Doctor Who serials,this brings up some fascinating moral questions. Also characters as well. Turlough for his part is the biggest puzzle. Himself somewhat the survivalist,he's an alien of some unknown origin here who is trapped living on Earth. And whether it be an allegiance to the black guardian or to the doctor,it's his youthful opportunism that is his motivating factor in his actions and not so much any moral motivation. One senses that the Doctor's motivations for taking him on as a companion is as much self protective as anything,considering Tegan and Nyssa's rightful skepticism of Turlough.