"But he wouldn't have taken it lying down!" he cried. "Hartley Parrish was a fighter, Bruce. Did you ever know a man who could best him? No, no, it won't fit! Besides ..."

He broke off and thought for an instant.

"We must get that letter from Harkings," he said presently. "Jeekes will have it. We can do nothing until ..."

His voice died away. Bruce, sunk in one of the big leather armchairs, was astonished to see him slip quickly away from the window and ensconce himself behind one of the chintz curtains.

"Here, Bruce," Robin called softly across the room. "Just come here.

But take care not to show yourself. Look out, keep behind the curtain and here ... peep out through this c.h.i.n.k!"

Young Wright peered through a narrow slit between the curtain and the window-frame. In the far corner of the courtyard beneath the windows, where a short round iron post marked a narrow pa.s.sage leading to the adjoining court, a man was standing. He wore a shabby suit and a blue handkerchief knotted about his neck served him as a subst.i.tute for the more conventional collar and tie. His body was more than half concealed by the side of the house along which the pa.s.sage ran. But his face was clearly distinguishable--a peaky, thin face, the upper part in the shadow of the peak of a discoloured tweed cap.

"He's been there on and off all the time we've been talking," said Robin. "I wasn't sure at first. But now I'm certain. He's watching these windows! Look!"

Briskly the watcher's head was withdrawn to emerge again, slowly and cautiously, in a little while.

"But who is he? What does he want?" asked Bruce.

"I haven't an idea," retorted Robin Greve. "But I could guess. Tell me, Bruce," he went on, stepping back from the window and motioning the boy to do the same, "did you notice anybody following you when you came here?"

Bruce shook his head.

"I'm pretty sure n.o.body did. You see, I came in from the Strand, down Middle Temple Lane. Once service has started at Temple Church there's not a mouse stirring in the Inn till the church is out. I think I should have noticed if any one had followed me up to your chambers ..."

Robin set his chin squarely.

"Then he came after me," he said. "Bruce, you'll have to go to Harkings and get that letter!"

"By all means," answered the boy. "But, I say, they won't much like me b.u.t.ting in, will they?"

"You'll have to say you came down to offer your sympathy, ... volunteer your services ... oh, anything. But you _must_ get that letter! Do you understand, Bruce? _You must get that letter_--if you have to steal it!"

The boy gave a long whistle.

"That's rather a tall order, isn't it?" he said.

Robin nodded. His face was very grave.

"Yes," he said presently, "I suppose it is. But there is something ...

something horrible behind this case, Bruce, something dark and ... and mysterious. And I mean to get to the bottom of it. With your help. Or alone!"

Bruce put his hand impulsively on the other's arm.

"You can count on me, you know," he said. "But don't you think ..."

He broke off shyly.

"What?"

"Don't you think you'd better tell me what you know. And what you suspect!"

Robin hesitated.

"Yes," he said, "that's fair. I suppose I ought. But there's not much to tell, Bruce. Just before Hartley Parrish was found dead, I asked Miss Trevert to marry me. I was too late. She was already engaged to Hartley Parrish. I was horrified ... I know some things about Parrish ... we had words and I went off. Five minutes later Miss Trevert went to fetch Parrish in to tea and heard a shot behind the locked door of the library. Horace Trevert got in through the window and found Parrish dead. Every one down at Harkings believes that I went in and threatened Parrish so that he committed suicide ..."

"Whom do you mean by every one?"

Robin laughed drily. "Mary Trevert, her mother, Horace Trevert ..."

"The police, too?"

"Certainly. The police more than anybody!"

"By Jove!" commented the boy.

"You ask me what I suspect," Robin continued. "I admit I have no positive proof. But I suspect that Hartley Parrish did not die by his own hand!"

Bruce Wright looked up with a startled expression on his face.

"You mean that he was murdered?"

"I do!"

"But how? Why?"

Then Robin told him of the experiment in the library, of the open window and of the bullet mark he had discovered in the rosery.

"What I want to know," he said, "and what I am determined to find out beyond any possible doubt, is whether the bullet found in Hartley Parrish's body was fired from _his_ pistol. But before we reach that point we have to explain how it happened that only one shot was heard and how a bullet which _apparently_ came from Parrish's pistol was found in his body ..."

"If Mr. Parrish was murdered, the murderer might have turned the gun round in Parrish's hand and forced him to shoot himself ..."

"Hardly," said Robin. "Remember, Mary Trevert was at the door when the shot was fired. Your theory presupposes the employment of force, in other words, a struggle. Miss Trevert heard no scuffling. No, I've thought of that.. it won't do ..."

"Have you any suspicion of who the murderer might be?"

Robin shook his head decidedly.

"Not a shadow of an idea," he affirmed positively. "But I have a notion that we shall find a clue in this letter which, like a blithering fool, I left on Parrish's desk. It's the first glimmer of hope I've seen yet ..."

Bruce Wright squared his shoulders and threw his head back.

"I'll get it for you," he said.

"Good boy," said Robin. "But, Bruce," he went on, "you'll have to go carefully. My name is mud in that house. You mustn't say you come from me. And if you ask boldly for the letter, they won't give it to you.

Jeekes might, if he's there and you approach him cautiously. But, for Heaven's sake, don't try any diplomacy on Manderton ... that's the Scotland Yard man. He's as wary as a fox and sharp as needles."

Bruce Wright b.u.t.toned up his coat with an air of finality.