Disease, war, and natural disasters have ended life on Earth as we know it. Amid the destruction, an 80 year old architect named Susannah has been commissioned to build an obelisk on Mars– something she will never see and never touch, but that will represent the art and creativity from her home planet, and be a memento of all humankind.

Because Earth has become virtually unlivable for most of its inhabitants, several colonies had been constructed on Mars, but none had been successful. The most promising project of all, called Red Oasis, had fallen when a disturbing Martian disease had evolved and killed all of the inhabitants– or so Susannah thought.

One afternoon, Susannah and her commissioner Nathaniel receive a message from a vehicle that seemed to belong to the forgotten Red Oasis colony. The message appears to be from a woman named Tory, who claims to be the last survivor of the colony. She says that she is alone with her two young children, and needs immediate assistance. Nathaniel doesn't believe that the message is coming from a real human– he thinks it's a trap to trick Susannah into destroying her project. It's revealed that Susannah lost both of her (adult) children to the horrors on Earth. Nathaniel fears that someone is toying with her emotions, knowing this specific personal history.

Despite the meaning, time, and effort that the obelisk represents for Susannah, she decides to dismantle it, in order to use the materials to save Tory and her children. Even at the expense of a long-lasting legacy, she refuses to sacrifice the possibility of a human life.