Sins is set in a nondescript coastal Kerala town. Father William is a local parish priest in his mid-30s, and a very good looking one at that. One day, his Ambassador collides into a bicycle and he literally bumps into Rosemary, a coy, naive young girl, in a tearing hurry to reach her examination venue. Father William offers to give her a lift and Rosemary agrees.
Taken in by his chivalry, good looks and dashing persona, a few weeks later, she visits him with gifts as a token of her appreciation. She asks father for his blessing. He grants it and plants a kiss on her forehead.
A sexual tension builds up between the two, a tension that receives vent, shortly a few weeks later, when in a moment of weakness, the two consummate their lust. The two become lovers, and the film tracks the path of their liaison. He experiences pangs of guilt and an internal conflict that tortures a man of his position who is sworn to celibacy.
Was the man of God actually a disciple of Satan all along? What is the church's role in this episode? Why is Rosemary's God-fearing Catholic family a silent spectator to her liaison with the priest?