‘Here is the first letter. You will see it is an application from William Douglas of Myrtle Cottage, Yelverton, South Devon, for particulars of annuities. He wanted to purchase one which would bring him in £500 a year. Here is our reply enclosing the information and a form for him to fill in, and here is the form which he returned to us duly filled. You will notice he is aged sixty-six. We then wrote him this letter explaining that the annuity would cost him £4600, and asking his further instructions. He replied, as you see, to proceed with the matter, and he would send on the cheque in due course. We prepared the necessary documents, but received no further communication from Mr Douglas until about ten days later we had this note stating that he regretted the trouble he had given, but that he found himself unable to proceed with the matter at present. And so it stands.’ ‘Then Douglas didn’t call here?’ ‘No.’ Tanner was considerably puzzled by this information. As he walked slowly along the Embankment back to the Yard, he racked his brains to understand Douglas’s motive or plan. What had been the ex-clerk’s idea? The figures of his bank account showed that at no time since he came to live at Yelverton had he had more than £600 to his credit. As he could not possibly have paid the four thousand odd himself, where did he expect to raise it? And then a sudden idea flashed into the Inspector’s mind. Sir William Ponson had been paying Douglas sums ranging from £100 to £400 at intervals during the last four years. These sums were all paid by cheques marked ‘X’ on the block. On the day before his death Sir William had written an ‘X’ cheque for £3000. This cheque had never been cashed. Was there not a connection? Had that £3000 ‘X’ cheque of Sir William’s not been written for the purpose of paying for Douglas’s annuity? It certainly looked like it. And had the sudden death of Sir William not prevented its being cashed? Of course, the amounts did not tally—the cheque was for £3000, while the price of the annuity was £4600. But it was obvious that these sums might represent the different opinions the two men held of what was due. Possibly also negotiations were in progress between them on the point. This was of course guesswork, but at least it would explain the facts. The Inspector walked like a man in a dream as he concentrated his thoughts on the whole circumstances. There seemed just one link of his chain missing—some one point which, if he could find it, would flood the whole of these mysterious happenings with light and make the disconnected facts he had learnt fall into their places like the closing pieces of a jigsaw puzzle. And then suddenly he wondered if he had not got it, as another and more sinister idea occurred to him. What if the business were blackmail? It had a nasty enough look. Could Douglas have got hold of something discreditable in Sir William’s life, and could the latter be paying for his silence?