Polio breaks out in Rio de Janeiro, the serum is in Santiago and there's only one way to get the medicine where it's desperately needed: flown in by daring pilots who risk the treacherous weather and forbidding peaks of the Andes.

　　In the year 2961, the time is after humanity and nature has recovered the land. A hunter named Cygnus is called to rise above his duty. He provides for Last Arc, a once nomadic band of survivors in need of food and water that is now growing scarce. The answer must be found before a group of outlandish Heretics descend upon them. Cygnus must voyage across the treacherous landscape to defend his people. Sent by Nova, the matriarch of the band, she acts based on her vision for Cygnus to find a seed of hope. The future of Last Arc is for him to discover, Cygnus ventures into a hostile landscape in search of an answer for his people. On this journey of encountering many traps and dangers, Cygnus discovers what has been hunting him is his identity.