"All the necessary arrangements have now been made with regard to your workshop at Tilbury. It is situated on the marshes close to the river, three miles east of the town and a mile to the west of Cunnock Creek. You can reach it either by the main road which runs half a mile inland, or by walking along the saltings under the sea-wall. "You cannot mistake the place, as it is an absolutely isolated building, consisting of a small cabin or hut, with a large shed attached for your work. It is not luxurious, but we have at least fitted up the interior of your living-room as comfortably as possible, and you will find in the shed everything that you specified in your list as being necessary for your experiments. "I should be glad if you would arrange to go down there and start work the day after tomorrow. There is a train from Fenchurch Street to Tilbury at 11.45 in the morning, and if you will catch that I will see that there is a trap to meet you at the station and drive you out along the road as near to the place as it is possible to get. This hardly gives you the full week in London which you wished for, but circumstances have arisen that make it of great importance to us to be able to place your invention on the market as quickly as possible. From your own point of view the sooner the work is done the sooner you will be in possession of funds, and so able to make any use of your liberty you choose. "Sonia has the keys of the building, and will give them you with this letter. "While you are working at the hut, it will be better, I think, if you stay entirely on the premises. I believe you will find everything you want in the way of food and cooking materials, and you will, of course, take down your own personal belongings with you. In the event of anything you really need having been forgotten, you can always walk into Tilbury, but I should strongly advise you not to do so, except in a case of absolute necessity. Apart from any danger of your being recognized, we are extremely anxious that no one connected with the powder trade should have the least idea that experiments are being conducted with regard to a new explosive. A large part of the immediate value of your invention will consist in its coming on the market as an absolute surprise. "I have been unexpectedly called away for a few days, but directly I return I shall come down to Tilbury and see you. Should you wish to communicate with me in the interval, you can do so by writing or wiring to me at the Hotel Russell, London, W.C. "I hope that you have enjoyed your well-earned if rather long-delayed holiday. "Your sincere friend, "L.J. McMURTRIE." I finished reading and slowly refolded the letter. "You know what this is about, of course, Sonia?" I said. She nodded again. "They want you to go down there at once. You must do it; you must do everything you are told just at present."