Two brothers, a priest apparently on the make and a cop formerly on the take, have a mutual business associate. The police dectective had collected a pittance for acting as bagman at the man's brothels, and the monsignor has received huge amounts for church charities by conferring a bogus respectability on the donor. A young prostitute is found dismembered. Her path had crossed that of nearly everyone in the film. . . Sounds like True Confessions the magazine, a byword for sordid revelations, doesn't it? Actually, none of the characters in this film killed her, and the man of God, whose ambitions are thwarted by the scandal, has committed no sin whatsoever, legal, moral or professional. This is a serious problem with the plot of the film "True Confessions," whose title refers to the unfortunate habit various people have of cornering the priest in the confessional to heap accusations at him and one another. The murder victim makes an exceedingly poor catalyst. But no matter. The film is taken not from the magazine, but from the book by John Gregory Dunne, who wrote the screenplay with his wife, Joan Didion. Whatever is wrong with the plot, there's nothing wrong with the dialogue. With the Dunne-Didion lines and the acting of Robert DeNiro (the priest) and Robert Duvall (the detective), the lack of a cohesive story doesn't seem terribly important. It's the contrast between the brothers that's the point -- the priest smooth and political, living neatly among polished wood, perfect lawns and order, troubling himself with refined philosophical questions; his brother crude and naive, living among peeling walls, dirt and sloppiness, dealing with the insoluble conflicts of humanity. The priest is a fascinating character, as are the sketched in portraits of a successful cardinal, played by Cyril Cusack, and an unsuccessful -- in worldly terms -- monsignor, played by Burgess Meredith. The question of a difficulty with his celibacy is a red herring; what troubles the young priest is his own proficiency at power manipulation, although his question, how else to endow the church with the ability to do good, goes unanswered. Besides, his brushes with humanity are so much more interesting than his brother's: On the homicide squad it's the same old sex- greed-murder business every day, but it's all in the priest's day's work to hear a father complain that his daughter the Carmelite is quitting the convent to become a professional bowler TRUE CONFESSIONS -- AMC Academy, NTI Arlington, NTI Landover, Roth's Randolph, Roth's Tysons Corner, Springfield Mall and West End Circle.