The surviving son of a germophobic mother, Cecil Reitmeister embraces all forms of bacteria and formulates an elaborate plan to lead humanity out of the Anthropocene and into a new era of interspecies harmony. His idiosyncratic plan requires years of experimentation and precise manipulation of his microbiome, the totality of microorganisms present in or on the human body. His mad-scientist mission leads to extreme social isolation, with the memory of his dead mother becoming his most frequent visitor. Cecil's quest to save the world comes to a screeching halt when his social worker and the police show up to condemn the only home he has ever known. Thrown in jail for assaulting the police, Cecil soon finds himself homeless and struggles to adjust to life on the streets. When he meets a group of Freegans (people who reject consumerism and seek to reduce waste by collecting discarded food) led by a magnetic red-headed woman, Cecil is forced to confront demons from his past and to reassess his self-imposed alienation, the rigidity of his worldview, and, ultimately, his plan to save humanity.