A gathering of those chosen in the 'Future-Oriented' realm, spears and shields, a bunker, and a life-risking mission to protect their loved ones. In the two paths of either regression or death, they search for each other with longing. Although nothing changes in the repeated missions, there is only one place they can return to. "The junior doesn't die before the senior. The junior is meant to live in place of the senior." ―Second unit leader of Spear and Shield, Lee Baek. "I'm the Doctor. Whatever you want, I'll make it happen." ―Ruler of Bunker Home, Doctor. "I'm happy to meet Senior Lee Baek. I'm so happy." ―Lee Baek's junior, Baek Gi, born from the manifestation of 'Survival of the Fittest.' In the face of repeated death, looking at and protecting each other was their way of loving.