When it comes down to children's shows and cartoons, there are many elements praised. Quality of works, the ability to tell mature stories or just general overall direction. One thing which is constantly praised by many is how certain ones manage to get away with dark or brooding elements without going utterly overboard.
One of the most famous and long standing examples is the Batman Animated Series, and rightfully so. It brought the Dark Knight away from the Silver Age incarnation people still regarded him as being, though Tim Burton definitely helped, and redid many famous villains with much more popular and often tragic backgrounds. A few other examples would be Exosquad, often regarded as the western world's equivilent of the original Gundam with neither side being entirely in the right, and even the X-Men Animated Series had some very dark moments. Anyone else remember Xavier forcing Magneto to relive his Holocaust memories to defeat him in one episode? The point is that there are a lot which have been praised, but there's one which seems to have been overlooked. One of Gerry Anderson's creations: Captain Scarlet.
No this isn't actually a joke. Just think about the main synopsis for the series for a moment:
If this sounds more like XCOM than it does Thunderbirds, you're not far from the content of many episodes. More than a few featured attempts to create new technology to detect Mysteron (the aliens') spies, with the humans trying desperately to learn something to give them an edge over their foe. It's some way in before they actually learn they are not indestructible and that they are actually capable of making mistakes. In a few of the episodes themselves, SPECTRUM (the human agents) would outright fail to stop the aliens in their mission with them assassinating or destroying something vital. Hell, the series even seemingly ended in an extremely costly base defense mission on the part of SPECTRUM.
Then there's the body count involved.
While Batman and even Spider-Man were known for having dark elements, both had heavy restrictions placed upon them by censors. Spider-Man wasn't allowed to even punch people most of the time, one of the more sane restrictions placed upon creators, and any time someone needed to be outright killed in the DCAU it was usually a robot or non-sentient henchman. In this series? A surprising number of episodes tended to feature a good six or so humans being killed on average, some just being innocent civilians, and that's not including the poor sap murdered so he could be replaced by the agent of the week. Or those who are not outright shown as dead by the Mysteron's attacks. More than once the Mysterons used suicide bombers, often in crowded rooms or with assaults which lead to massive collateral damage. Often the show displayed the impact of the bombs themselves but never address casualty figures in full. These also tended to be only the showier efforts from earlier on in the series.
As episodes went by, the Mysterons seemed to evolve in their attacks to use less overt methods and more subtle but effective ones. One of the more effective examples is when sabotage of air supply system at a surface to orbit missile base is sabotaged, leading to the deaths of just over three hundred personnel inside. Oh, and yes we see them all during the aftermath quite dead.
The series also didn't hesitate to show its heroes, or humanity itself, in a bad light either. The entire covert war actually begins as a result of human representatives turning violent when they stumble across a Mysteron city during a first contact. Before either could speak, and after the demi-Darth Vader voice impressed upon the audience the Mysterons wanted to just speak with them, the humans panicked and opened fire. The following barrage wrecking the city and leading to both the war and the first human abductees to be turned into their agents. Other episodes featured military commanders butting heads with SPECTRUM, wanting to escalate the war into something far worse. Beyond that, the entire opening pilot to the series featured Scarlet under full Mysteron control after being killed and fighting SPECTRUM forces. It's only sometime later that he, or rather his duplicate, switches sides.
So why isn't the series better remembered when it took steps further than some of its later counterparts? Most likely visual presentation and advancements in storytelling with television.
While the aforementioned Batman TAS and Spider-Man TAS were both near constantly set shadowed cities and dark environments despite their overtly dressed foes, Captain Scarlet looked just like any other Gerry Anderson production. The sets are brightly lit, the futuristic designs colourful and the environments relatively utopian at times. None really fitted the apparent tone of the war with even the Mysteron city looking like a glorified sweet shop more than an alien civilisation. This isn't to bash on the aesthetics or designs, many of the vehicles especially have aged well, just that they didn't do much to help inspire any feelings of a interstellar terrorist war. Also, the limitations of expressiveness when it came to the puppets likely didn't help.
Beyond the visuals, many storytelling elements were much cruder than those seen today. Many characters were far from deep or complex, even the hero himself and there was little development as time passed. There's also little impact of the Mysterons' actual victories or progress within the war itself, the series lacking the better continuity of the later examples. Furthermore the villains themselves never evolved beyond being a faceless menace, meaning they lacked the link or ability to build upon any elements of their existence which the other shows benefited from.
Even tonally the program did not seem to be able to embrace grim elements quite as well as later shows, despite the obvious qualities on display.
While the series' flaws are apparent to anyone viewing, it's still a show which tends to be criminally overlooked when creators managed to get stuff into children's television. With higher deaths, greater failures and more of a general war feel than many other shows, it gives some insight into why censors might have become so strict in later years and in the development of series' storytelling, It's just a shame the series tends to be overlooked when people speak of darker or more serious programs aged at younger audiences. It certainly got away with more than most would today.