“Am I to open it?”

“Please.”

I unfolded a sheet of ruled note-paper of the most ordinary variety.  It had been opened and laid flat, and on it, in black ink, was a crude drawing of the deck of the Ella, as one would look down on it from aloft.  Here and there were small crosses in red ink, and, overlying it all from bow to stern, a red axe.  Around the border, not written, but printed in childish letters, were the words:  “Not yet.  Ha, ha.”  In a corner was a drawing of a gallows, or what passes in the everyday mind for a gallows, and in the opposite corner an open book.

“You see,” she said, “it was mailed downtown late this afternoon.  The hotel got it at seven o’clock.  Marshall wanted to get a detective, but I thought of you.  I knew—­you knew the boat, and then—­you had said—­”

“Anything in all the world that I can do to help you, I will do,” I said, looking at her.  And the thing that I could not keep out of my eyes made her drop hers.

“Sweet little document!” said McWhirter, looking over my shoulder.  “Sent by some one with a nice disposition.  What do the crosses mark?”

“The location of the bodies when found,” I explained—­“these three.  This looks like the place where Burns lay unconscious.  That one near the rail I don’t know about, nor this by the mainmast.”

“We thought they might mark places, clues, perhaps, that had been overlooked.  The whole—­the whole document is a taunt, isn’t it?  The scaffold, and the axe, and ‘not yet’; a piece of bravado!”

“Right you are,” said McWhirter admiringly.  “A little escape of glee from somebody who’s laughing too soon.  One-thirty—­it will soon be the proper hour for something to happen on the Ella, won’t it?  If that was sent by some member of the crew—­and it looks like it; they are loose to-day—­the quicker we follow it up, the better, if there’s anything to follow.”

“We thought if you would go early in the morning, before any of them make an excuse to go back on board—­”

“We will go right away; but, please—­don’t build too much on this.  It’s a good possibility, that’s all.  Will the watchman let us on board?”

“We thought of that.  Here is a note to him from Marshall, and—­ will you do us one more kindness?”

“I will.”

“Then—­if you should find anything, bring it to us; to the police; later, if you must, but to us first.”

“When?”

“In the morning.  We will not leave until we hear from you.”

She held out her hand, first to McWhirter, then to me.  I kept it a little longer than I should have, perhaps, and she did not take it away.

“It is such a comfort,” she said, “to have you with us and not against us!  For Marshall didn’t do it, Leslie—­I mean—­it is hard for me to think of you as Dr. Leslie!  He didn’t do it.  At first, we thought he might have, and he was delirious and could not reassure us.  He swears he did not.  I think, just at first, he was afraid he had done it; but he did not.  I believe that, and you must.”