Cayley put the bag in the bottom of the boat, stepped in, and using an oar as a punt-pole, pushed slowly off.  Then, very silently, he rowed towards the middle of the pond.

He had stopped.  The oars rested on the water.  He picked up the bag from between his feet, leant over the nose of the boat, and rested it lightly on the water for a moment.  Then he let go.  It sank slowly.  He waited there, watching; afraid, perhaps, that it might rise again.  Antony began to count ....

And now Cayley was back at his starting-place.  He tied up the boat, looked carefully round to see that he had left no traces behind him, and then turned to the water again.  For a long time, as it seemed to the watchers, he stood there, very big, very silent, in the moonlight.  At last he seemed satisfied.  Whatever his secret was, he had hidden it; and so with a gentle sigh, as unmistakable to Antony as if he had heard it, Cayley turned away and vanished again as quietly as he had come.

Antony gave him three minutes, and stepped out from the trees.  He waited there for Bill to join him.

“Six,” whispered Bill.

Antony nodded.

“I’m going round to the front of the house.  You get back to your tree and watch, in case Cayley comes again.  Your bedroom is the left-hand end one, and Cayley’s the end but one?  Is that right?”

Bill nodded.

“Right.  Wait in hiding till I come back.  I don’t know how long I shall be, but don’t be impatient.  It will seem longer than it is.”  He patted Bill on the shoulder, and with a smile and a nod of the head he left him there.

What was in the bag?  What could Cayley want to hide other than a key or a revolver?  Keys and revolvers sink of themselves; no need to put them in a bag first.  What was in the bag?  Something which wouldn’t sink of itself; something which needed to be helped with stones before it would hide itself safely in the mud.

Well, they would find that out.  There was no object in worrying about it now.  Bill had a dirty night’s work in front of him.  But where was the body which Antony had expected so confidently or, if there were no body, where was Mark?

More immediately, however, where was Cayley?  As quickly as he could Antony had got to the front of the house and was now lying in the shrubbery which bordered the lawn, waiting for the light to go up in Cayley’s window.  If it went up in Bill’s window, then they were discovered.  It would mean that Cayley had glanced into Bill’s room, had been suspicious of the dummy figure in the bed, and had turned up the light to make sure.  After that, it was war between them.  But if it went up in Cayley’s room—­

There was a light.  Antony felt a sudden thrill of excitement.  It was in Bill’s room.  War!

The light stayed there, shining vividly, for a wind had come up, blowing the moon behind a cloud, and casting a shadow over the rest of the house.  Bill had left his curtains undrawn.  It was careless of him; the first stupid thing he had done, but—­