Frank Donnelly is a physics professor at a Philadelphia university and a Catholic priest; a rare combination. What may be more unusual is that Frank is also married, one of less than a hundred such priests in the United States. When his wife is killed in a tragic accident Frank is left to raise his young daughter alone. Three years later he falls in love with Vicki Meyers, a teacher in the parish school at St. Elizabeth's where he ministers on weekends, herself a widow with a young son.
The Vatican is not amused by Frank's petition to remarry and that is not his only problem. He has been receiving threatening emails suggesting that he is not a "true" priest and he teams up with a woman detective investigating the possible murder of a priest who had received similar emails.
Frank and Vicki's love grows as they take their children to birthday parties, the zoo, playgrounds, and soccer matches even as their hope fades for a positive response to Frank's petition. Meanwhile, in his physics lab the sudden and very strange behavior of some cosmic rays can't be explained scientifically. As a scientist he is reluctant to consider a supernatural explanation, but the Vatican is not and worried enough for Frank to apply a little "ecclesiastical blackmail" in support of his petition.