On the eve of World War II, the German Kurt Müller, his American-born wife Sara, and their three children, having lived in Europe for years, visit Sara's wealthy mother near Washington, DC. Kurt secretly works for the anti-Nazi resistance. A visiting Romanian count, becoming aware of this, seeks to blackmail him.

When Day, a sunny fellow, encounters Night, a stranger of distinctly darker moods, sparks fly! Day and Night are frightened and suspicious of each other at first, and quickly get off on the wrong foot. But as they discover each other's unique qualities--and come to realize that each of them offers a different window onto the same world-the friendship helps both to gain a new perspective.

After an unusual meteor shower leaves most of the human population blind, a merchant navy officer must find a way to conquer tall, aggressive plants which are feeding on people and animals.