Mark marries Marnie although she is a habitual thief and has serious psychological problems, and tries to help her confront and resolve them.

Marnie Edgar: Why don't you love me, Mama?
Mark Rutland: Well why didn't you jump over the side?
Marnie Edgar: The idea was to kill myself, not feed the damn fish.
Marnie Edgar: You don't love me. I'm just something you've caught! You think I'm some sort of animal you've trapped!
Mark Rutland: That's right - you are. And I've caught something really wild this time, haven't I? I've tracked you and caught you and by God I'm going to keep you.
Bernice Edgar: Oh, Marnie. You shouldn't spend all your money on me like you do.
Marnie Edgar: But that's what money's for: to spend. Like the Bible says, "Money
[first lines]
Sidney Strutt: Robbed! Cleaned out! $9,967! Precisely as I told you over the telephone. And that girl did it. Marion Holland. That's the girl. Marion Holland.
First Detective: Can you describe her Mr. Strutt?
Sidney Strutt: Certainly I can describe her: five-five, 110 pounds, size 8 dress, blue eyes, black wavy hair, even features, good teeth.
Sidney Strutt: [detectives unable to restrain laughter] Well what's so damn funny? There's been a grand larceny committed on these premises.
Marnie Edgar: Can't you understand? Isn't it plain enough? I cannot bear to be handled.
Mark Rutland: By anybody? Or just me?
Marnie Edgar: You... Men!
Mark Rutland: Really? You didn't seem to mind at my office that day, or at the stables. And all this last week i've handled you.
Mark Rutland: What you do need, I suspect, is a psychiatrist.
Marnie Edgar: Oh, men! You say "no thanks" to one of them and BINGO! You're a candidate for the funny farm.
Marnie Edgar: I don't believe in luck.
Mark Rutland: What do you believe in?
Marnie Edgar: Nothing.
Mark Rutland: Did you have a tough childhood, Miss Taylor?
Marnie Edgar: Not particularly.
Mark Rutland: I think you did. I think you've had a hard, tough climb.
Mark Rutland: Before I was drafted into Rutland's Miss Taylor, I had notions of being a zoologist. I still try to keep up with my field.
Marnie Edgar: Zoos?
Mark Rutland: Instinctual behavior.
Marnie Edgar: A lady's instinct too?
Lil Mainwaring: I'm queer for liars.
Marnie Edgar: Are you still in the mood for killing?
Mark Rutland: You're very sexy with your face clean.
Mark Rutland: When we get home, I'll explain that we had a lover's quarrel... That you ran away... That I went after you and brought you back. That'll please Dad. He admires action. Then I'll explain that we' re gonna be married before the week is out... That I can't bear to have you out of my sight. He also admires wholesome animal lust.
Bernice Edgar: Oh, Marnie. You shouldn't spend all your money on me like you do.
Marnie Edgar: But that's what money's for: to spend. Like the Bible says, "Money answereth all things."
Marnie Edgar: You Freud, me Jane?
Mr. Rutland: The best thing for the inside of a man or a woman is the outside of a horse.
Mark Rutland: You should try to be Marnie's friend.
Lil Mainwaring: I always thought a girl's best friend was her mother!
Marnie Edgar: How did you find me?
Mark Rutland: You're here to answer the questions old girl.
Mark Rutland: But I do want to go to bed, Marnie. I very much want to go to bed.
Mark Rutland: I'm fighting a powerful impulse to beat the hell out of you.
Mark Rutland: Atlantic City opens for races at the end of the month. We could drive out there next Saturday...
Marnie Edgar: All right. Are you fond of horses?
Mark Rutland: No, not at all.
Lil Mainwaring: How do you take your tea, Miss Taylor?
Marnie Edgar: Usually with a cup of hot water and a tea bag.
Marnie Edgar: Oh... it's you. Where's my Mother?
Jessica 'Jessie' Cotton: She's making a Pecan pie... for me.
Marnie Edgar: That figures!
Mark Rutland: Marnie, it's time to have a little compassion for yourself. When a child, a child of any age, Marnie, can't get love, it takes what it can get, any way it can get it. It's not so hard to understand.
Marnie Edgar: Oh - it's you. Where's my Mother?
Hotel Chauffeur: She's making a Pecan pie. For me.
Marnie Edgar: That figures.
Mark Rutland: Here we are old bean, the homestead.