To most of you, the world of crime is a never-never-land, because in your own mind crimes are something which happen to other people, and which therefore really don't affect you. But you're laboring under a delusion... Tonight's file opens aboard a small boat called the Eldorado, used by Dr Henry Wilson and his wife in their search for rare specimens of sea life. 

***Quality alert - there is some audible crackling on this show.***