- Slade: [Referring to the death masks of killers in the black museum] You treat them like trophies... like a stuffed elk head mounted over the fireplace.
- Insp. Paul Warwick: Yes, a little, but these were more dangerous than an elk. Man unfortunately is the most dangerous of all beasts.
- Slade: Man is not beast.
- Insp. Paul Warwick: Murderers are beasts.
- Lily Bonner: It's at night that interesting things happen. What kind of work do you do at night, Mr. Slade?
- Slade: I doubt if you'd be interested.
- Lily Bonner: Do you just work?
- Slade: Sometimes I walk close by the river. The river is like liquid night flowing peacefully out to infinity.
- [last lines]
- Constable #2: [as they are looking for Slade's body in the river] It's too dark, and it's too deep.
- Insp. Paul Warwick: Not so dark and not so deep as where he's going.
- Slade: Yes, I will tell you. My mother was an actress. She was one of the most angelically beautiful women who ever lived, exquisitely graceful, talented, and captivating. I loved her deeply... deeply. She had the face of heaven and the wretched heart of Jezebel. For every aspect of beauty she possessed, she contained a double portion of evil. I hated her!
- Lily Bonner: But I thought you said you loved her?
- Slade: I can love the beauty and hate the evil. Didn't you know that, Miss Bonner?
- Chief Insp. Melville: [Referring to the police dragnet] Can't get out of this if he's human.
- Insp. Paul Warwick: Afraid he isn't human... not and do what he did to that girl.
- William Harley: This person George Bernard Shaw should be shipped back to Ireland post-haste.
- Helen Harley: What did you say dear?
- William Harley: I was talking to the dog.
- Helen Harley: About what dear?
- William Harley: I said George Bernard Shaw should be sent back to Ireland.
- Helen Harley: Why, what did he say that you don't like?
- William Harley: He said that if a Duchess went down to Whitechapel and got slaughtered by Jack the Ripper, something would be done to protect the lives of the poor women who live there.
- Chief Insp. Melville: Her Majesty has decided that the Ripper can't possibly be an Englishman. Now I suppose will have to investigate all foreigners.
- Lily Bonner: And when you've tested it and proved it, what will you know Mr Slade?
- Slade: A little more about life and death.
- Lily Bonner: I wonder what else you need to know about life except that it is wonderfully worth living.