The girl walked naked out of nowhere on a winter night and to psychiatrist Paul Fidler it was as if one of his own obsessive visions of disaster took human form, bringing nightmares to life. Tiny, appearing harmless, she had half killed a man who tried to assault her. Piquantly lovely, she belonged to no known racial type. Of high intelligence, she spoke a language no one could be found to understand. Most remarkable of all, commonplace objects like clothing and cars were a mystery to her. They called her "Urchin." Has she truly wandered out of her own familiar world and been cast adrift - the loneliest of all lonely people - in another branch of the universe? As he scrapes at the barriers of secrecy that surround Urchin, Paul's life collapses about him until he has nothing left but Urchin herself and the vision she has given him of a world far better than he has ever known. But does he really have either?