“Thank you, sir; you are always thoughtful for men who are working with you.  It is a pleasure to me to be with you again.  I shall go back to Scotland Yard and report to my chief.  Then I shall call at Chatwood’s; and I shall return here as soon as possible.  I suppose I may take it, miss, that I may put up here for a day or two, if required.  It may be some help, or possibly some comfort to you, if I am about, until we unravel this mystery.”

“I shall be very grateful to you.”  He looked keenly at her for a few seconds before he spoke again.

“Before I go have I permission to look about your Father’s table and desk?  There might be something which would give us a clue—­or a lead at all events.”  Her answer was so unequivocal as almost to surprise him.

“You have the fullest possible permission to do anything which may help us in this dreadful trouble—­to discover what it is that is wrong with my Father, or which may shield him in the future!”

He began at once a systematic search of the dressing-table, and after that of the writing-table in the room.  In one of the drawers he found a letter sealed; this he brought at once across the room and handed to Miss Trelawny.

“A letter—­directed to me—­and in my Father’s hand!” she said as she eagerly opened it.  I watched her face as she began to read; but seeing at once that Sergeant Daw kept his keen eyes on her face, unflinchingly watching every flitting expression, I kept my eyes henceforth fixed on his.  When Miss Trelawny had read her letter through, I had in my mind a conviction, which, however, I kept locked in my own heart.  Amongst the suspicions in the mind of the Detective was one, rather perhaps potential than definite, of Miss Trelawny herself.

For several minutes Miss Trelawny held the letter in her hand with her eyes downcast, thinking.  Then she read it carefully again; this time the varying expressions were intensified, and I thought I could easily follow them.  When she had finished the second reading, she paused again.  Then, though with some reluctance, she handed the letter to the Detective.  He read it eagerly but with unchanging face; read it a second time, and then handed it back with a bow.  She paused a little again, and then handed it to me.  As she did so she raised her eyes to mine for a single moment appealingly; a swift blush spread over her pale cheeks and forehead.

With mingled feelings I took it, but, all said, I was glad.  She did not show any perturbation in giving the letter to the Detective—­she might not have shown any to anyone else.  But to me. . .  I feared to follow the thought further; but read on, conscious that the eyes of both Miss Trelawny and the Detective were fixed on me.