Hetty moved instinctively to her lover\'s side. His face was ghastly pale, but he held his head high and looked Prout proudly in the eyes. The latter waited. He had made no accusation; it was not his cue to express an opinion one way or another. Hetty looked at him approvingly.

"If there is anything wrong about the notes," Capper began, "I can only----"

"From your point of view there is nothing wrong," said Prout. "A mere coincidence, sir. If I could only, have a few minutes\' private conversation with you, doctor?"

Bruce led the way outside. He was utterly bewildered. Those notes had passed into his possession quite honestly, they were for value received, and they never left his possession until he parted with them to Capper. Why, they were in his possession hours before he was called into the corner house.

The strangely assorted trio turned into a tea room close by. They had a table to themselves where they could talk freely.

"Now say it all over again," Bruce asked. "I am perfectly dazed. Let me know what I am accused of doing."

Prout replied that for the present there was no accusation.

"It\'s like this," he said, laying the fateful notes on the table. "A man who has got to be identified is found dead--murdered, beyond a doubt, in an unoccupied house in Raven Street. All the circumstances of the case point to robbery. On searching the body we find a letter written by the deceased to a friend saying that he is forwarding some banknotes. He gives the number of those banknotes amongst others--numbers 190753 to 190793. All this is set out clearly in the letter. Now, will you please to examine those notes, doctor, and tell me the numbers?"

Bruce turned them over one by one. There was no mistake about the matter at all. They were the same numbers as those given in the handwriting of the dead man. The whole thing seemed impossible, but there it was.

"One moment," Hetty asked eagerly. "How do you know that the letter in your possession really was written by the murdered man?"

Prout glanced admiringly into the pretty flushed face.

"That\'s a clever question, miss," he said, "but I have a reply to it. We have found a woman near the docks where the unknown stayed for a day or two. As she cannot read or write she got him to write her a line or two to her landlord\'s agent, sending some arrears of rent and promising the balance shortly. That scrap of paper has come into my possession."

"And of course it tallies," Bruce said moodily. "Those things always do."

"It does, sir," Prout went on. "The question of handwriting is established. How those notes came into your possession we have yet to find out."

"They never came into my possession," Bruce cried. "There is some mistake----"

Prout tapped the pile of papers significantly.

"Here they are, with your signature on the back of every one of them," he said. "There is nothing singular about that, seeing that so many tradesmen insist upon having banknotes endorsed. Question is, What\'s the explanation?"

For the life of him Bruce could not say. It was absurd to suppose that by some mistake the Bank of England had issued two sets of notes of the same series of numbers. There was no mistake about the murdered man\'s letter either.

"Perhaps you\'d like to tell your story, sir," Prout suggested.

"My story is quite simple," Bruce replied. "Some little time ago I bought a picture by J. Halbin. I gave a few pounds for it. Early in the evening of the day preceding the corner house murder I had a visitor. He was an elderly Dutchman, who gave his name as Max Kronin. He had heard of my purchase............