Complex sentence: The story is set in the near future, when Earth is threatened by a spaceborne virus that turns humans into violent creatures and enhanced soldiers are fighting a war against the creatures in order to ensure the survival of the human race.
Split into simpler sentences: The story is set in the near future, when Earth is threatened by a spaceborne virus that turns humans into violent creatures. Enhanced soldiers are fighting a war against the creatures in order to ensure the survival of the human race.