A software engineer at General Dexterity, a San Francisco robotics company with world-changing ambitions, Lois Clary codes all day and collapses at night, her human contact limited to the two brothers who run the neighborhood hole-in-the-wall from which she orders dinner every evening. When the brothers have Visa issues, they have one last delivery for Lois: their culture, the sourdough starter used to bake their bread. She must keep it alive, they tell her-- and learn to bake with it. Soon Lois is providing loaves to the General Dexterity cafeteria, then the farmer's market, and a whole new world opens up-- including a secret market that aims to fuse food and technology.