On the eve of a national conference Zelda (Underground Railway Theater Artistic Director, Debra Wise), an acclaimed evolutionary biologist, is visited by Rachel, an ambitious graduate student. The two women share a zeal for science, a bold and contrarian approach to the male-dominated field, and much more. During the course of the visit, the young scholar challenges the older woman’s “grandmother hypothesis” with a radical theory of her own that she believes will change the way people regard sex. Emotion and evolution clash with humor and passion in Sarah Treem’s (HBO’s In Treatment) new play about the competitiveness and sacrifices needed to succeed as a woman in science.