An unusual 'monster' story, this, in that the aliens are portrayed with an unusual degree of depth and sympathy, and the monsters turn out to be humans after all - albeit ones inadvertently driven mad by the aliens!
The early sequences on board Maitland's spaceship are very well done, with an atmosphere of sinister intrigue built up around the unseen-as-yet Sensorites and what their powers may be. When we get to see the creatures, they are surprisingly well-rendered; the domed heads, lidless eyes and mouthless faces capture an 'alien' quality far better than other man-in-a-suit creations managed ten or twenty years later. That they are (mostly) essentially friendly comes as a bit of a shock after some earlier species(!), and in fact seem pathetically vulnerable to loud noises and darkness. The fact that without their various badges of office they all look the same is later exploited nicely as a major plot device - like in 'The Aztecs', there is an interesting powerplay going on between the different factions.
The scenes set on the SenseSphere wisely do not stretch the budget too much, by sticking to a small number of locations, and the sequences with the travellers guiding each other physically and mentally through the aqueducts are built well towards the climax - which alas fails to appear, as the story just seems to end without any excitement at all. Otherwise, a diverting tale, and one given an unlikely amount of balance in its portrayal of the alien/human relationships - and I should mention that the departing shot of Maitland's ship disappearing into the distance of space is flat-out lovely.
Episodes watched: 29
Episodes still to watch: 693