The scene I quote here takes place toward the film's end. Robert MacGregor (Liam Neeson) is a Scots clansman who has become an outlaw through no misdeeds of his own; he has borrowed money from the Marquis of Montrose (John Hurt), whose nephew, Cunningham (Tim Roth), has stolen the money and left MacGregor in debt. The Marquis does suspect that his nephew is behind the whole thing, but preserving his own rank is more important to him, so he allows MacGregor to be pursued across Scotland, entrusting this very task to the vile Cunningham, who at one point goes so far as to rape MacGregor's wife, Mary (Jessica Lange). So, by the end of the film when MacGregor has arranged to settle all in a duel to the death with Cunningham, Mary is pregnant with a child that may either be Robert's, or Cunningham's. The following scene of farewell takes place just before Robert leaves with the Duke of Argyle for the duel.
ROBERT: So, boys! Have you heard there's going to be another addition to the family?
Robert's two sons look at Mary, who glances in turn at Robert, surprise in her eyes.
ROBERT: Show them where it's hid, Mary.
Mary remains still.
ROBERT'S SON: Is it inside you?
ROBERT'S SON: How does it get out?
Mary and Robert exchange glances, and Roy smiles.
ROBERT: The same road it got in.
Robert grabs his jacket and heads outside, where the Duke of Argyle and his party await him. Mary comes running to him from behind.
MARY: Robert...Robert...what if you don't--
MARY: No. I cannot.
She pulls his tartan up onto his shouler.
MARY: What if--
Robert puts a finger to her lips.
MARY: I cannot. What if you do not return to us?
ROBERT: If it's a boy, call him Robert. (beat) If a lass, name her for my love, Mary McGregor.
Of course, the scene is helped by the pitch-perfect acting of Neeson and Lange, and by Carter Burwell's gorgeous score (which, by the way, is a fascinatingly "minimalist" score that eschews the heavy-handed gestures common in such melodramatic films). The duel that follows between Robert and Cunningham is one of the best such action sequences ever filmed, driven as it is almost entirely by character concerns as opposed to plot machinery. And Tim Roth's performance is quite simply one of the best portrayals of a villain ever.
But the scene above is why I love Rob Roy. The film establishes Robert MacGregor as a man of honor and integrity, a man for whom doing the right thing and holding his word is more important than anything. His unquestioning acceptance of the child who may be Cunningham's -- and the film, wisely, never provides a conclusive answer to this question, or even raises it again -- is the best example of it.
(Another good bit of love dialogue from this film is Robert's single line, which he repeats several times to his wife: "Mary MacGregor, do you know how fine you are to me?")