`But I always thought you were dead against amateurs„' said the General. `Of course you can hardly call the doctor, an amateur, but… '
Hadley shook his head. `Sir Basil Thomson, one of the greatest men the Yard ever had, used to say that a detective had to be jack of all trades and a master of none. The only thing I regret about the doctor here is the deliberate way he patterns himself after the detectives in sensational fiction; of which, by the way, he's an omnivorous, reader. His silences. His mysterious "Aha's!" his….’
`Thank you,' rumbled Dr Fell, satirically. He had put on his cloak and his long shovel-hat. Stumping round near the door, he accepted a glass from Parker. `Hadley,' he continued, `that's an outworn maxim, and a baseless slur on a noble branch of literature. You say that the detective in fiction is mysterious and slyly secret. All right; but he only reflects real life. What about the genuine detective? He is the one who looks mysterious, says "Aha!" and assures everybody that there will be an arrest within twenty-four hours.. In other words, he has all the pose, whether he has the knowledge or not. But, like the fictional detective, very sensibly he doesn't tell what he thinks, for the excellent and commonplace reason that he may be wrong.'
`All right,' said Hadley, — resignedly. 'If you like. Well, good health, gentlemen..!' He drained his glass and put it down. `I' suppose, doctor, this is a preamble to some mysterious predictions of yours?'
`I hadn't thought of doing so,' he replied. `But as a matter of fact, I will give you three hints about what I think. I won't elaborate them' — his scowl became ferocious as he saw Hadley's grin `because I may be wrong. Ha!'
`I thought so. Well, number one?'
`Number one is this. There was some dispute about the time Driscoll died. The only period in which we seem absolutely to be able to fix it lies between one-thirty when he was seen by Parker lighting a cigarette at the rail in front of Traitors' Gate, and ten minutes to two, which is the time
Doctor Watson said he died. Mr Arbor, coming into Water Lane at twenty-five minutes, to two, was positive there was nobody near the rail.'
`I don't see any implication there,' General Mason said, after a pause; `unless it's the implication that Arbor was lying. What's your second hint?'
`The second hint,' Dr Fell answered, `concerns that crossbow bolt. It was, as you saw, filed sharp into a deadly weapon. Now you are assuming, quite naturally, that this filing was done by the murderer.' We have also noticed that the same hand had started to file off those words, Souvenir de Carcassonne, but had stopped with three letters neatly effaced, and gone no farther…. Why weren't those other letters effaced? When we found the body, we were of course bound to learn of the bolt Mrs Bitton purchased at Carcassonne, and, since the victim was Driscoll, it would be too monstrous to assume a mere coincidence. I repeat: why weren't those letters effaced?'