“Two of you will watch him,” said Lord Linchmere.  “And now, Dr. Hamilton, if you will return with me to my room, I will give you the explanation which my horror of scandal has perhaps caused me to delay too long.  Come what may, you will never have cause to regret your share in this night’s work.

“The case may be made clear in a very few words,” he continued, when we were alone.  “My poor brother-in-law is one of the best fellows upon earth, a loving husband and an estimable father, but he comes from a stock which is deeply tainted with insanity.  He has more than once had homicidal outbreaks, which are the more painful because his inclination is always to attack the very person to whom he is most attached.  His son was sent away to school to avoid this danger, and then came an attempt upon my sister, his wife, from which she escaped with injuries that you may have observed when you met her in London.  You understand that he knows nothing of the matter when he is in his sound senses, and would ridicule the suggestion that he could under any circumstances injure those whom he loves so dearly.  It is often, as you know, a characteristic of such maladies that it is absolutely impossible to convince the man who suffers from them of their existence.

“Our great object was, of course, to get him under restraint before he could stain his hands with blood, but the matter was full of difficulty.  He is a recluse in his habits, and would not see any medical man.  Besides, it was necessary for our purpose that the medical man should convince himself of his insanity; and he is sane as you or I, save on these very rare occasions.  But, fortunately, before he has these attacks he always shows certain premonitory symptoms, which are providential danger-signals, warning us to be upon our guard.  The chief of these is that nervous contortion of the forehead which you must have observed.  This is a phenomenon which always appears from three to four days before his attacks of frenzy.  The moment it showed itself his wife came into town on some pretext, and took refuge in my house in Brook Street.

“It remained for me to convince a medical man of Sir Thomas’s insanity, without which it was impossible to put him where he could do no harm.  The first problem was how to get a medical man into his house.  I bethought me of his interest in beetles, and his love for anyone who shared his tastes.  I advertised, therefore, and was fortunate enough to find in you the very man I wanted.  A stout companion was necessary, for I knew that the lunacy could only be proved by a murderous assault, and I had every reason to believe that that assault would be made upon myself, since he had the warmest regard for me in his moments of sanity.  I think your intelligence will supply all the rest.  I did not know that the attack would come by night, but I thought it very probable, for the crises of such cases usually do occur in the early hours of the morning.  I am a very nervous man myself, but I saw no other way in which I could remove this terrible danger from my sister’s life.  I need not ask you whether you are willing to sign the lunacy papers.”