Swapped In The Apocalypse

The deep freeze had lasted ten years when Vincent went to the border to build the wall meant to hold the cold back. While he was away, the nanny in his house swapped the children. His daughter Cheryl was put in the basement and kept there, cold and hungry, close to dying. Lily took her place in the household and was raised on everything that would have been Cheryl's. Before he left, Vincent had prepared a shelter stocked with heat and supplies and set it to open only to Cheryl's iris. Nobody in the house knew it existed. Ten years on he comes home to find the girl he has been told is his daughter is not.