Big mistake. But the man, Tom, gives in to his wife's importuning as she manipulates him into keeping the baby. She has lost three children, one just recently stillborn, and he cannot find it easy to deny her this child washed up on their shore with no identifying clues except for an expensive silver rattle.
Even after Tom suspects who the real mother might be, another grieving woman who has lost both husband and child, he is loath to reveal the truth about the little girl that people think is his own.
Recommendation: I found this novel very thought-provoking, a look at the dynamics of childlessness and some reasons behind child abductions, a not too infrequent occurrence. Conscience, empathy, honor and loyalty all come into play in this story. Well written and developed, it's a novel I heartily recommend.