Lucas has inherited his mother's bakery, as well as her obsession for baking sourdough: a bread conceived by wild strains of yeast, and ripened until its flavor becomes both pungent and startling. Running the family business was a safe bet for Lucas, and a lucrative one at that; but when he finds that his soul has become infused with the same untamable character of the sourdough itself, he discovers that a safe bet can be the most dangerous thing a person can dare to make.