FAQ

In season 1 the enemy are the original aliens from the 1950s invasion who have been reanimated. They appear as giant frog-like creatures in their natural form but can take over human bodies for a period before the radiation they emit destroys the host who often display tell-tale radiation burns. There are tens of thousands of aliens worldwide; most governments are aware of them and have formed their own special units to deal with them, the series focusing on the American team. In season 2 a second wave of aliens arrive and destroy the original aliens for their failure. They number only 100 or so , are purely human in appearance, and they brought with them the alien deity 'The Immortal'. They can no longer take over human bodies but can create clones of prisoners they take to do their bidding. They use these clones to infiltrate the US government and attack the American team, killing Drake and Ironhorse. Unable to trust the authorities any longer, the team go underground to fight a guerilla-style war against the aliens who are situated in the same city, itself wracked by a second Great Depression (possibly the result of alien sabotage).