SOURDOUGH is a sneaky little book. It reels you in with maps and menus and a spunky young software programmer named Lois Clary, who moves to San Francisco from Michigan to accept a job with General Dexterity. She spends long days coding the proprioception module of ArmOS, the company’s robotic arm, and when she returns home to her expensive, tiny apartment on Cabrillo Street, she pulls a package of nutritive gel from her refrigerator. Until one day, a menu from Clement Street Soup and Sourdough waves from her door. She dials the number and orders a combo, double spicy, the first of a month of nights of delivered dinners from Beoreg and Chaiman, the brothers who run the shop. “The soup was so hot it burned the frustration out of me, and I went to bed feeling like a fresh plate, scalded and scraped clean.”

"Like Robin Sloan’s previous book, MR. PENUMBRA’S 24-HOUR BOOKSTORE, SOURDOUGH invites us into a world of tech geeks and traditionalists, and adds a sly dose of magic."

Sadly for Lois’ mental and digestive health, the brothers soon confide to their “number one eater” that they must leave town due to visa troubles. They’re moving to Berlin to find another second floor apartment. Beoreg wants to open a real restaurant, with tables and chairs and waiters. But before they go, they bestow a gift on Lois: the sourdough starter in a ceramic pot. “The gray slime inside looked distinctly not alive. It looked like an enemy of aliveness. Like something alive things crossed the street to avoid.” Reluctantly, Lois promises to keep it alive. Before the brothers disappear into their waiting taxi, Beoreg hastily shows her how to feed it flour and water, and leaves her with a mixing bowl and a long-handled spoon. Lois approaches the challenge of the starter with her usual problem-solving skills, starting with a book on sourdough by Everett Broom.

“I opened my laptop, called up the website of an expedient internet retailer, and pecked in the name of the scale --- the precise brand and model that Broom recommended. The site immediately responded: CUSTOMERS WHO BOUGHT THIS ITEM ALSO BOUGHT…followed by the bench knife. And the knife blade. The baking stone. King Arthur flour and Diamond Crystal Salt, just as Everett Broom recommended. And finally, Broom’s book itself.

The internet: always proving that you’re not quite a special as you suspected.”

While her first attempt at breadmaking in her kitchen is hilariously messy, the resulting loaf has a face: “It was an illusion, of course.” A compelling illusion. It is also delicious, and Lois is hooked. Soon she is building a rustic brick oven in the backyard of her apartment, maniacally baking loaf after loaf long into the night. The sourdough starter glistens and sings in its ceramic crock. Her obsession animates her soulless coding as she trains a robotic arm to stir bread dough and even to crack an egg. Various food and technology leaders thwart and aid her as she moves her act across the San Francisco Bay into the Marrow Fair, a compendium of wacky and brilliant experimenters with food, subsidized by the mysterious Mr. Marrow. She’s successful, she’s stimulated, she’s exhausted, but she’s increasingly concerned about the malevolent magic of the starter.

Like Robin Sloan’s previous book, MR. PENUMBRA’S 24-HOUR BOOKSTORE, SOURDOUGH invites us into a world of tech geeks and traditionalists, and adds a sly dose of magic. I loved Lois for so many reasons: for being a woman in a male-dominated field, for following her passion without a map of where it will lead. The prose winks at you with double entendres: for example, the German industrial oven Lois acquires in the Marrow Fair is called a Faustofen. Funny and readable, the book nevertheless poses potent questions about what constitutes “life.” When is it acceptable to mess with it, to recombine it?