- Policeman: Orders to shoot on sight... I thought he said the bloke was invisible?
- Willie Spears: Where are you? Where are you?
- Geoffrey Radcliffe: Here beside you!
- Willie Spears: But, but I can't see you!
- Geoffrey Radcliffe: Of course you can't, I'm a ghost.
- Willie Spears: [Gasps] Ghost!
- Geoffrey Radcliffe: [Sneezes]
- Willie Spears: What kinda ghosts sneeze?
- Geoffrey Radcliffe: It's cold in the other world, so cold!
- Sampson: You and Radcliffe were great friends, weren't you doctor?
- Doctor Frank Griffin: We still are, I'm happy to say.
- Sampson: Yes doctor - quite so. The research on which you and he were collaborating was interrupted by the unfortunate... accident, to Sir Michael, shall we say? And to carry on such important work man like you wouldn't hesitate to break the law, would you?
- Doctor Frank Griffin: Suppose you come to the point, Inspector?
- Sampson: I've been looking up the file on your late brother. That was nine years ago, wasn't it? Very ingenious. He concocted a formula which included a poisonous drug called Duocaine. An extraction of an East Indian herb that took the colour out of things. Combined with other ingredients known only to himself, it made the body transparent when injected into the bloodstream. Very ingenious.
- Helen Manson: Helen to Geoffrey as he removes his bandages and clothes to leave, "When will I see you"?
- [first lines]
- Mr. Cotton: I - I can't believe it's going to happen. Just two more hours, and they're going to kill him.