In his much-anticipated new novel, Robin Sloan does for the world of food what he did for the world of books in Mr. Penumbra's 24-hour bookstore. Lois Clary is a software programmer at General Dexterity, a robotics company with typical San Franciscan world-changing ambitions. She codes all day and collapses at night, her human contact limited to the two brothers who run the neighborhood hole-in from which she orders, and savors, dinner every evening. Then, disaster! Visa issues. The brothers close up shop, and fast. But they have one last delviery for Lois: their culture, the sourdough starter brought from afar, used to bake their bread. She must keep it alive, they tell her - feed it daily, play it music, and please, please: learn to bake with it. Lois is no baker, but she could use a roommate, even if it is a needy colony of micro-organisms. Soon, not only is she eating her own homemade bread, she's providing loaves daily to the General Dexterity cafeteria. The company chef urges her to take her product to the farmers market. A whole new world opens up. When Lois comes before the jury that decides who sells what at Bay Area markets, she encounters a close-knit club with little appetite for new members. Then an alternative emerges: a secret market, literally underground, that aims to fuse food and technology. It might be perfect for the programmer-turned-baker. But who are these people, exactly? And who is the mysterious Mr. Marrow presiding over it all? Leavened by the same infectious intelligence that made Mr. Penumbra's 24-Hour Bookstore such a sensation, but taking on even more substantial challenges, Sourdough marks the triumphant return of a unique and beloved young writer. --