The House That Stood Still by A.E. Van Vogt was published in 1950, and sometimes published as Undercover Aliens. - Allison stephens knew there was something mysterious about the house and the people in it. Then he stumbles on the space ship and learned of the atomic war soon to destroy the earth. He also found the strange people who lived for hundreds of years and possessed the knowledge of centuries.. they could have saved mankind.. but instead they planned to escape to another planet.