"Go on," she replied curtly.
"Mark," said Amberley, "did not fall into the river because he was drunk. He was drunk, of course very drunk — but he was pushed in. Being drunk, he drowned. It was a murder planned so cleverly that I doubt whether it could ever have been brought home to Fountain. Mark's habits were a byword in Upper Nettlefold; several persons had wondered aloud how it was that he hadn't stumbled into the river long since. It is also a wellknown fact that at this season of the year the mist that lies over the Weald after dark is nearly always pretty thick in that hollow where the road runs beside the Nettle. Fountain trusted to luck - or perhaps knew—- that Tucker would not be following Mark particularly closely. For Mark's death Inspector Fraser was indirectly responsible. He gave Tucker to understand that he was being put on to that job merely to humour a whim of mine."
The sergeant coughed. "Be making a report, sir?"
"I shall, Sergeant, but don't interrupt. Fountain gave out that he was going to London that afternoon. He probably did go. If he hadn't had any luck in what he meant to do I have no doubt that he would have repeated the manoeuvre next day. But he had luck. It all turned out as he had expected. He left his car probably in one of the lanes leading on to the main road and lay in wait for Mark beside the river where the fog was thickest. When Mark appeared he had only to push him over the bank. I don't suppose it required much strength, and in any case Fountain was a very powerful man. The river is fairly deep; Mark drowned, being too drunk to make any effort to save himself."
"Yes, but supposing he hadn't drowned?" objected Anthony.
"That would have been annoying for Fountain, of course, but not dangerous. If the boy had said that someone pushed him in, who would have believed him?"
"You would," said Anthony.
"Possibly, but although Fountain was suspicious of me he never knew how much I'd found out. No, the thing was safe enough - and it worked. Had the mist been less thick, had Collins not lost sight, temporarily, of Mark, it would not have worked. But Collins was too late to save the boy's life, though there is no doubt that he putt forth superhuman efforts to do so. From the moment that Fountain learned of his cousins' presence in Upper Nettlefold Collins was on the watch. He knew Fountain better than I did. His story about the cigarette case, Sergeant, was quite untrue, but I daresay Miss Fountain would have confirmed it, wouldn't you, Shirley?"
She nodded. "I was completely in his power. If he had the will, I dared not give him away. That was partly why I didnt confide in you. He suspected you from the start of knowing much more than the police."
"And therefore it was unsafe to confide in me lest I should betray my knowledge? Many thanks. Now, on the day following the murder Fountain came to call on me at Greythorne. Ostensibly his object was to inquire into Collins' presence on the scene. Actually he came to discover, if he could, what I was thinking and whether you, Shirley, were remaining at Ivy Cottage. I gave him to understand that I suspected Collins and also that you were rernaining at the cottage. Since he had eliminated Mark I expected him to make an attempt on you next, and my plan was to catch him in the act and arrest both him and Collins on two separate charges. I should have been able to do that very successfully had it not been for the well-meaning but disastrous zeal of Corkran. When I took you to the cottage to collect your things, Shirley, I unbolted the back door and appropriated the key. Having desposited you at the Boar's Head I motored back to Greythorne and rang up Peterson, telling him to keep an eye on Fountain and let me know if he left the house that night. You came into the room in the middle of that conversation, Felicity, and remarked that I had sweet telephone manners. Do you remember? Peterson rang me up just after midnight to say that Fountain had left the house and gone off on a push-bike. I then got on to you, Sergeant, and we drove to Ivy Cottage to await his arrival. Then, when things were panning out almost miraculously well, Corkran gave the alarm and Fountain escaped by the back door. You were rather fed up with me for letting him go, weren't you? To have stopped him would have been sheer folly. I couldn't prove a thing against him except that he had broken into a strange house. It had its amusing side, of course. Not only did you follow him, but Peterson, having caught sight of you pedalling down the drive, followed you both. Unnecessary but equally zealous. He didn't recognise you, and fearing that I might be surprised by two criminals instead of one, came along to lend a hand. I saw him when I went to bolt the back door, and he was ust going to come and speak to me when he caught sight of you, Anthony, and tactfully beat a retreat. "That was Fountain's first attempt to murder Shirley. It is my belief that he meant it to look like suicide - the reason being Mark's death. Not a bad idea. But I gave you a clue, Sergeant, and I think - I really think you ought to have guessed a little more than you did. I pointed out to you that whoever broke into the cottage evidently did not know that Miss Fountain owned a bull terrier. Collins did know that, for he had been to the place before. I am sad, Sergeant; sad and disillusioned."