Days of Grass is a novel set several generations after the invasion of earth. Esther is a girl living in an underground shelter, with the descendants of people who fled there during the take over.

Esther learns of a path up to the surface, visiting there although it is forbidden, and when she is finally caught, she is unexpectedly befriended by the reclusive leader of the community, Standish.

Esther despises the other members of the community, seeing it as stagnant and useless, no one goes to the surface, no oe learns new things. As she matures, her contact with Standish and his knowledge changes her view of the world and their place in it.

As she grows older, Esther learns about the invading aliens and about the problems the community is facing, but it is not until the death of Standish that things change forever.