Nathan Feldman, a fortyish Jewish professor of philosophy, returns to his condo complex after a Saturday morning walk only to find that his name is no longer on his mailbox. The key to his condo isn't in his pocket, and a resident across the hall, a good friend, refuses to buzz him in because she claims not to know him. As it turns out, no one recognizes him. He cannot find his wallet or cell phone. He suddenly has no way to prove who he is. He walks...