Still sort of vaguely attached to the United Nations specialist outfit "UNIT", the "Doctor" (Jon Pertwee) arrives to meet with the "Brigadier" (Nicholas Courtney) and discuss some mysteriously vanishing scientists. He sets up a tracking mechanism and is swiftly heading to find out what is going on. What he doesn't know is that the enthusiastic journalist "Sarah Jane" (Elisabeth Sladen) has stowed away on the TARDIS. Not only that, but they are back in medieval England and amidst a conflict between "Irongron" (David Daker) and "Edward of Wessex" (Alan Rowe). To make matters even worse, it transpires that he is not the only futuristic visitor. "Linx" has crashed his "Sontaran" ship and needs to get it repaired so he can get back to his intergalactic warmongering. To that end, he has done a deal with "Irongron" to provide him with powerful weapons (i.e. muskets) in exchange for assistance. When "LInx" realises it's the legendary "Doctor" on his trail, things become rather more menacing for all concerned. It's good for the production to get out of Television Centre for much of this, and it gives us plenty of axe-wielding, bows and arrows at a castle complete with a dungeon. The arrival of the feisty Sladen also breathes some new life into the series, too. There are just the four parts to this, and that helps keep the story moving along quickly and entertainingly as the battle of wits between the two extra-terrestrials hots up and the warring families have a good old stink-bomb fight!