The sandy-haired clerk hummed and hesitated.  “Well, I believe he’s going, sir,” he answered at last; “but it’s a bit uncertain.  He’s a fidgety man, the Professor.  He came down here this morning and asked to see the list, the same as you have done.  Then he engaged a berth provisionally—­’mind, provisionally,’ he said—­that’s why his name is only put in on the list in pencil.  I take it he’s waiting to know whether a party of friends he wishes to meet are going also.”

“Or wishes to avoid,” I thought to myself, inwardly; but I did not say so.  I asked instead, “Is he coming again?”

“Yes, I think so:  at 5.30.”

“And she sails at seven?”

“At seven, punctually.  Passengers must be aboard by half-past six at latest.”

“Very good,” I answered, making up my mind promptly.  “I only called to know the Professor’s movements.  Don’t mention to him that I came.  I may look in again myself an hour or two later.”

“You don’t want a passage, sir?  You may be the friend he’s expecting.”

“No, I don’t want a passage—­not at present certainly.”  Then I ventured on a bold stroke.  “Look here,” I said, leaning across towards him, and assuming a confidential tone:  “I am a private detective”—­which was perfectly true in essence—­“and I’m dogging the Professor, who, for all his eminence, is gravely suspected of a great crime.  If you will help me, I will make it worth your while.  Let us understand one another.  I offer you a five-pound note to say nothing of all this to him.”

The sallow clerk’s fishy eye glistened.  “You can depend upon me,” he answered, with an acquiescent nod.  I judged that he did not often get the chance of earning some eighty rupees so easily.

I scribbled a hasty note and sent it round to Hilda:  “Pack your boxes at once, and hold yourself in readiness to embark on the Vindhya at six o’clock precisely.”  Then I put my own things straight; and waited at the club till a quarter to six.  At that time I strolled on unconcernedly into the office.  A cab outside held Hilda and our luggage.  I had arranged it all meanwhile by letter.

“Professor Sebastian been here again?” I asked.

“Yes, sir; he’s been here; and he looked over the list again; and he’s taken his passage.  But he muttered something about eavesdroppers, and said that if he wasn’t satisfied when he got on board, he would return at once and ask for a cabin in exchange by the next steamer.”

“That will do,” I answered, slipping the promised five-pound note into the clerk’s open palm, which closed over it convulsively.  “Talked about eavesdroppers, did he?  Then he knows he’s been shadowed.  It may console you to learn that you are instrumental in furthering the aims of justice and unmasking a cruel and wicked conspiracy.  Now, the next thing is this:  I want two berths at once by this very steamer—­one for myself—­name of Cumberledge; one for a lady—­name of Wade; and look sharp about it.”