Two decades into his career, Tom Limbeck, a New York City social worker, is leading an orderly, utterly prosaic life. He is, by self-description, a poor man's psychiatrist, dedicated to helping his clients see things rationally, the better to confront the real world. He works in an office beset by budgetary difficulties and driven to solutions suited only to the bureaucracy. Tom's life changes when he takes on the case of Michael, who is known as Saint Francis of the Dumpster for his peaceful disposition and practice of eating from garbage cans. Tom is at first haunted by, then obsessed with, this uncommunicative young man who holds a precious secret which causes him to risk his survival by living on the street. Tom is determined to discover and expose Michael's secret (his faith/his delusion) as a necessary first step before any treatment can begin. Tom cannot reason his way out of his own obsession when he finds himself bending the rules, abandoning therapeutic norms and, before long, stalking his client. Parts of a World is a book about doubt-doubt, faith, and delusion.