Following on from Mind of Evil, this serial is a bit shorter and also a bit simpler in its construction. The plot lets the viewer into the inside from the start, since it is clear that the spacecraft approaching Earth is filled with nastiness, even if the humans only get to see the Gold Man Group version, and are taken in by their offer of peace and technology. From here we get a bit of trickery and betrayal as we head towards the inevitable scenes of monsters walking at soldiers against a backdrop of an abandoned airstrip or factory grounds. This is essentially what we get with this serial since there is little room for much else; for example there isn't really a central idea here, just monsters and betrayal.
That said it does still do the job since it plays it fairly straight and without too much padding. The characters are mostly broad caricatures in the various supporting role, and this reflects their use within the plot. Generally the plotting and the characters lack shading and detail, instead just fulfilling their broad roles within the narrative. The monsters themselves do work well though; the spaceship looks very much like a cheaper TV set and attempts to give it an organic feel later on are not wholly successful, but the monsters are actually pretty effective. Okay they are basically the same as many others in terms of their modus operandi, but their messy organic appearance full of wet-looking tendrils and nodules was pretty effective. They are helped by the way they are filmed since the camera and the audio effects have a decent stab at a creepy unsettling presentation of them.
The main cast do okay with all of this (although for the regularly dispatched UNIT soldiers, they barely get a day's work out of this serial); mainly this is because the show is running through the basics with a decent enough pace, so it gives them enough to do without ever making things too difficult. This works well for them all, but again the chance to have some very good interplaying between the Doctor and the Master is not really made the most of. It does all still work reasonably well though, and in some ways it is interesting in how it is delivered, but generally it is not one that really jumps out as being great (although it also doesn't standout as bad either.
