- Philo Vance: [to Heath] Sergeant, you're much too trusting for this deceitful world. If everything happened as easy as that, life would be very simple and very dull.
- Belle Dillard: [as Sprigg and Arnesson enter] Eric, Eric! I'm so glad you're here. Robin's been killed!
- John E. Sprigg: Robin?
- Sigurd Arnesson: Cock Robin. Well, his name was against him, wasn't it?
- Ernest Heath: Well, you know, Mr. Vance, I got nothin' against theories - except that you can't hang 'em!
- Ernest Heath: [to Sperling, who is unresponsive] Well, young fella, you thought you'd get away, did yuh? Oh, you're one of those silent lads, are you? Say, we'll have you talkin' so much that lockjaw will look like a case of St. Vitus dance!
- Sigurd Arnesson: [to Belle] You must put Robin out of your head, cruel and unnecessary as his death seems. Life is cruel, but what can we crawling microbes do about it? Not that you aren't a very charming microbe.
- Philo Vance: [to Markham and Heath] You know, gentlemen, this is no ordinary case. We cannot proceed in an ordinary manner. Mark my words, this is not a single murder that we are trying to solve. It is the beginning of a series of murders... ghastly and inhuman!
- Philo Vance: My dear Miss Dillard, our problem is to match normal thinking against the abnormal scheming of a criminal mind.
- Ernest Heath: [to cleaning woman vacuuming in hall] It's about time you had some respect for the hand of the law!
- cleaning woman: [Sarcastically] The hand of the law! The only thing I see around here is a lot of flat feet!
- Ernest Heath: [Insulted] Is that so?
- [She starts vacuuming again and his blustery mumbling is drowned out by the vacuum. He walks down the hall and pulls out the plug in order to have the last laugh]
- Ernest Heath: Oh. yeah?
- Professor Bertrand Dillard: [to Belle] When you are young, all wounds heal and in time are forgotten.