But “Philomena” focuses on yet another matter: the church’s role in isolating unwed mothers like Ms. Lee and forcing them to put their babies up for adoption to families willing to make large contributions. Rights advocates charge that rather than prioritize the welfare of the mother or the children involved by finding suitable adoptees, the church was interested only in ensuring the couples were Catholic and, preferably, wealthy.

Church officials have denied that payment ever took place, and many of the documents from that period were lost in a fire. But researchers say that between 1945 and the mid-1960s, at least 2,200 infants and toddlers like Anthony, some of whom had stayed with their mothers for years, were sent to America.

Those were only a portion of the forced adoptions. Probably 50,000 babies were born in Mother and Baby homes throughout Ireland before they closed in the 1990s. Conditions in the homes were difficult for the young mothers. The church saw them as degenerates, not fit to keep their children. Among other humiliations, they were forced to recount their sexual encounters in detail to the nuns. The father of Ms. Lee’s son was a young man she had met one evening at a carnival. They had planned to meet the following week, but her aunt would not allow it.

Over 50 years, Ms. Lee sent word to the convent in Roscrea every time she moved, just in case Anthony ever came looking for her, and she visited several times pressing for information about him.

But to no avail, even though Anthony, renamed Michael Hess and raised by a Missouri family, had also been trying to find her and had made his way to Roscrea. Mr. Hess, who became a prominent Washington lawyer — with a stint as chief legal counsel to the first President George Bush — was repeatedly told that nothing could be done.

As he was dying of AIDS in 1995, he requested that his ashes be buried at the convent, in case his mother should ever come looking for him. Why the nuns never helped is unclear. The nuns involved died long ago.