When they get there they notice that London in the far, far future is much less inhabited than they remember. In fact, it's grown over and looks a lot less like London and more like Dartmoor where the episode was filmed. They soon discover that they are not alone, and in fact there are other humans there who have been drawn to the dead planet by a distress call. The 'astronauts' are from one of Earth's many colonies, and when informed that there are a bunch of "super-humans" on board Nerva they aren't too impressed. They are, however, paranoid and turns out that they've been hunted by some monster since they arrived, and several members of the original crew have vanished.
After all three explorers are separated by various stupid plot devices (Harry falls down a crevasse, Sarah Jane just falls in with one of the astronauts, they all discover that they're being manipulated by an advance Sontaran scout and his tin robot. Sontarans are a returning alien race in the Whoniverse, looking quite like potatoes with eyes, they're all clones of one-another and a most militaristic race indeed. They been at war with their solar-system neighbors the Rutan host for centuries, but are in this time period, search for other planets to invade. The scout, who is called Styre, has been sent by the Sontaran Empire to text the limits of the human race prior to a massive invasion. He freely experiments on the astronauts, starving, torturing and forcing them to perform ridiculous strength tests to discern whether or not they'll be a factor in their invasion.
The single sontaran is no match for our intrepid gang, and all is set right. There is a singularly hilarious moment when the Doctor actually fights Styre in hand-to-hand combat, however apparently Tom Baker had broken his collarbone in an earlier stunt, and was replaced in the sequence by a stunt-man.
Thankfully this story was only two episodes, and while it showcases the BBC's ability to shoot an entire story on location (and conveniently not have to move the TARDIS prop) it's brevity is matched only by it's complete silliness. Sontarans alone, while in number are quite strong, are pretty weak, though still strong enough to capture several frail humans. In the revived series Sontarans would be redesigned to look a bit less silly and have been pumped up in strength, but still fall short of being a "classic" villain race like the Daleks or Cybermen.
Still they have a decent amount of collectibles, though most are based on their more recent appearances. The current Character Options line of 5 inch figures sports a number of different Sontarans, including named characters and generic army-builder "troopers". There's even a 4 pack with three Sontarans and a Donna Noble figure from last season's "The Sontaran Stratagem." Being a "classic" alien race they've been made into all sorts of odds and sods, including this 3 inch metal figurine that I found on eBay:
This review would not be complete if I omitted a couple of salient pieces of trivia (oxymoron much?). First, the TARDIS does not make an appearance in this episode at all. Secondly, the entire hour of story was filmed on location with no interiors at all. There are a few shots of the inside of Styre's space pod, but it's not a full set. Strangely the Sontarans don't have communication devices in their ships either, Styre uses a separate view screen to talk to his superiors, which becomes unintentionally funny when you realize that both Sontarans are being played by the same actor in the same costume. It's also a continuation of the long "arc" story that began with Robot our first review. The story ends with the Doctor, Sarah Jane and Ian beaming back to Space Station Nerva. Of course, their beam doesn't quite reach the station right away, and we're set up for an epic six-part episode that we'll be reviewing next.
This story is also too short to have much future impact on the Doctor or his mates. There's very little character development here, though there are a few funny moments with Sarah Jane and Harry, it's clear that the writers were kind of in a quandry because of the casting of Baker. Baker was much younger than they had expected, so they had created the character of Harry Sullivan to be the younger, more action oriented character. In fact, Sullivan is also a medical doctor so he serves many of the same functions as our main Doctor.
Our next story promises much, much more, just from it's title alone: next up - The Genesis of the Daleks