“You realize, don’t you, that I’m out here on a specific job? I’m here to investigate the possible leakage of information to the enemy. My peace-time job as a C.I.D. man has nothing to do with my present employment. But for the suggestion that Mrs. Rubrick’s death may have some connection with our particular problem I should not have come. It’s with the knowledge and at the invitation of my colleagues that I’m here.”

“I got a rise with my bait then,” said Fabian. “What did you think of my brain child?”

‘They showed me the blueprints. Beyond me, of course. I’m not a gunner. But I could at least appreciate its importance and also the extreme necessity of keeping your work secret. It is from that point of view, I believe, that the suggestion of espionage has cropped up?”

“Yes. To my mind it’s an absurd suggestion. We work in a room that is locked when we’re not in it and the papers and gear — any of them that matter — are always shut up in a safe.”

“We?”

“Douglas Grace has worked with me. He’s done the practical stuff. My side is purely theoretical. I was at Home when war broke out and took an inglorious part in the now mercifully forgotten Norwegian campaign. I picked up rheumatic fever but, with an extraordinarily bad sense of timing, got back into active service just in time to get a crack on the head at Dunkirk.” Fabian paused for a moment as if he had been about to say something further but now changed his mind. “Ah well,” he said, “there it was. Later on still when I was supposed to be fairly fit they put me into a special show in England. That’s when I got the germ of the idea. I cracked up again rather thoroughly and they kicked me out for good. While I was still too groggy to defend myself, Flossie, who was Home on a visit, bore down upon me and conceived the idea of bringing her poor English nephew-in-law back with her to recuperate in this country. She said she was used to looking after invalids, meaning poor old Arthur’s endocarditis. I started messing about with my notion soon after I got here.”