Carnal Craving by Ray Gordon

Sent to a convent in Hertfordshire by her fanatically religious stepfather, Mary is forced to endure the hardest of regimes. But Mary is blossoming, with sexual stirrings that have no boundaries. As her desire grows, fueled by an affair with Sister Elizabeth, Mary finds herself on a collision course with the mother superior. When she is caught in the act, her punishment is severe, but it's only a matter of time before the tables are truly turned.