In late 19th century New York City, Olivia de Havilland is Katherine Sloper, a shy young woman whose wealthy physician-father believes she may turn into a spinster. Attending a party along with her widowed aunt, she meets Montgomery Clift as Morris Townsend, a handsome young man of no definite future or position.
When we learn that Katherine will come into some fortune as her father's only child, and that Morris is seeking employment, we appreciate her father's suspicion that Morris is after her money. Our suspicion is deepened when Morris asks her to marry him, and advises her to resist her father's insinuation that he is after her money.
The climax builds further when Morris' sister has an interview with Dr. Sloper which does not assuage his feelings. After a combative confrontation in which Katherine states that she will marry against her father's will. Morris however wishes the Doctor's approval and so allows the Doctor to take his daughter Katherine to Europe for six months. Her father thinks that the separation will make her forgot Morris, or that Morris will forget her. But it doesn't have that effect.
Her father now takes her intransigence as his opportunity to verbally cut her down to nothing. Katherine and Morris decide to elope that very night. She tells him that she and her father can never reconcile. That however means her fortune will be only one-third of what it would have been. She waits for Morris to come for her that night and he fails to show.
"I can be very cruel. I have been taught — by masters"