Helium (2017)

The far future. It has been over three hundred years since the Great War ended, but there were no victors. Eighty-five per cent of the Earth's surface now lies beneath a vast gaseous ocean known as the Poison Belt - a toxic, mutated cocktail of biological and chemical weapons designed by both sides to win the war. Instead, it almost spelt extinction for the human race. Those that survived cling to the High Lands - alpine valleys and mountaintop islands, safe from the noxious fog, and ply the clean air in ships of all description. Meanwhile, beneath the Belt, rumours of life abound...