From the Publisher:
When a baby is abandoned on the doorstep of a young socialite widow, the woman thinks she knows the identity of the father: her deceased writer husband, the cad! But who is the mother? Reluctantly, Nero Wolfe accepts the case, and Archie identifies the first clue: unusual buttons on the baby's overalls.
Rex Stout: The Mother Hunt. A Nero Wolfe Mystery. Introduction by Marilyn Wallace. Crimeline, ISBN: 0553247379 (May, 1993), 224 p., $5.99