A Belgian astronomer now based in London, Johann Mayer discovers what appears to be cloud of dust from some form of activity upon the Moon and is excited to have his personal beliefs of the existence of ''Moon men'' confirmed.
He initially keeps this secret but as the clouds increase in size and appear to start to form an atmosphere he feels he has to confide in his peers, one of which reports this to the palace and King George III. There's nothing that can be done but it is monitored and a swathe of magicians, priests and soothsayers visit the palace with various theories on the Moon crisis, the atmosphere thickens and vegetation can even be seen growing, this first story arc concludes with the Moon beginning to rotate like a planet, which brings a apocalyptic tension over the entire Earth.
Aliens have now terraformed the Moon so they use it as a a base for there operations on Earth or maybe as a short term place for their people to reside if they cannot save their own planet in time. They appear first in France but not as their true selves, more like a holographic image of a humanised version of the monsters they really are, as they do not want to stir up panic amongst the humans at this stage. They explain to King Louis XV that they mean no harm but have stay on the Moon indefinitely because they have been exiled from their world by revolting peasants, something the French Kings might well believe and they tell the humans that they are the royal family of their own planet.
They cannot leave their ships as the Earth's atmosphere is toxic to them. They tell the humans they have no intention of invading Earth but want to mine some materials to create cities on the moon which will be their new home, they really need to create a slave worker force to extract all the radioactive elements from the Earth's crust and ship them back to their world as a fuel resource because their world's supplies are spent. This is the main theme of the second arc.
Unbeknownst to Europeans the aliens eventually establish some small domed settlements in isolated parts of the world like South America, Australia and the poles to work on the possibilities of terraforming the Earth and to research the pathogens that may harm the aliens as well as food sources for the invasion crew.
The aliens manipulate the King and set France against other European countries to create wars as a way of reducing the population of Earth, as they cannot hope to control the entire Earth population so they want to make the population more manageable for when they can eventually invade. These domes become of interest to indigenous peoples of course and there are interactions of different types between them and the aliens.
Johann Mayer now travels from England to France because he is obsessed with rumours of the ''Moon men'' and wants to be a part of the action and is eventually captured by the aliens after he unwittingly discovers their true motive for being here, which concludes the third story arc.
There are flare ups between the aliens and the humans at various times particularly when the aliens holographic generating equipment fails and they are seen as their true selves. The aliens do not have advanced weaponry that you might expect as they have never needed them, only having advanced technologies for survival and space travel. The plan of raping the Earth of radioactive elements is one of pure necessity but they must be brutal to save their own civilization but there are reluctant aliens and some who think there may be alternative options. The aliens manipulate the humans in many other ways such as spreading the plague and small pox.
Meanwhile all the time the aliens have to keep the technologies to keep the Moon's atmosphere appropriate for their survival, which leads to tensions between the high command and the worker aliens as well as the stress from being so far from home and having to commit genocide of one people for their own people to survive. This tension creates a political struggle between the alien high command and the technicians which turns violent as the alien revolters become aware of Mayer being on the Moon and he tells them of Earth's rich environments and peoples that will be destroyed or enslaved. This is the climax for the fourth arc.
Ongoing, I see many of possibilities for great story about political, romantic and violent interactions between the aliens and the various peoples of Earth and their rulers, and bringing in more story in detail from the aliens dying planet. Another arc I would like to develop is too introduce a team of scientists who are working in various fields to vanquish the alien threat and want to bring down a alien ship to collect specimens for experimentation.
The the astronomers/scientists headed by Johann Mayer, wife Michelle and his son Thomas.
The Royal families of Britain, France and other countries.
The alien high commands various officers.
The aliens running the Moon atmosphere operations.
The aliens on the doomed home planet.
The indigenous peoples living around the alien domed settlements.
The stories of some regular citizens of Earth.
I would present an insight into all the characters lives regarding family, romance and other relationships with the life altering stressful background of the ever present story arc of the aliens/moon/invasion crisis.