an officerââ
âThe idea that an officer killed Lieutenant Fortesque is quite out of the question,â Carstairs said.
Blackstone grinned. âThatâs not what you said to Captain Huxton,â he pointed out.
âI have since revised my position,â Carstairs told him.
Blackstone shook his head. âNo, you havenât. You were never prepared to consider it.â
âAre you calling me a liar?â Carstairs demanded.
âNo,â Blackstone said. âIâm calling you a tactician .â
âAnd what exactly do you mean by that?â
âYou didnât want Huxton involved in this investigation, not because you think heâs a fool â which he undoubtedly is â but because youâd already decided I need to be tightly controlled, and heâs clearly not up to the job. Thatâs why you were baiting him from the moment I arrived. Thatâs why you pretended to agree with me about the possibility of the killer being an officer â because you wanted him to storm out, just as he eventually did.â
âWhatever I may have said, and for whatever reason I may have said it, my position now is quite clear,â Carstairs told Blackstone, in the growling voice of a wounded beast. âI consider it unthinkable that one of my officers would contemplate, even for a moment, anything as dastardly as committing a murder.â
âThatâs not quite what you mean,â Blackstone said.
âNo?â
âNo. What youâre actually saying is that itâs unthinkable that any of the officers serving under you would contemplate killing one of their own kind .â
âThatâs the same thing, isnât it?â Carstairs asked, sounding genuinely mystified.
âNot by a mile,â Blackstone told him.
Then he reached down for the whisky bottle and poured himself a shot.
âWhat the devil  . . .â Carstairs exclaimed.
âYou did offer me a whisky earlier,â Blackstone said, looking him squarely in the eye.
âDonât push me too far,â Carstairs said.
âIâll try not to,â Blackstone promised. He took a sip of his drink. It was malt â far beyond the pocket of a humble police inspector. âIn my time, Iâve arrested a wide range of people, from the lowest guttersnipe in an East End flophouse to members of the aristocracy in their own stately piles. And the main lesson Iâve learned from making those arrests is that, given the right circumstances, anybody is capable of killing anybody.â
âThatâs preposterous!â Carstairs said.
âIs it?â Blackstone asked. âWhen I reached for your whisky just now, wasnât there a brief moment when you wanted to kill me?â
Carstairs looked distinctly uncomfortable. âI wouldnât put it quite as strongly as that,â he said.
âThe feeling might have only lasted a split second, but for that split second, you did want me dead,â Blackstone told him. âThereâs no point in denying it, because I could read it in your eyes.â
âBalderdash,â Carstairs said, unconvincingly.
âYou wouldnât have reacted like that if Iâd been one of your young lieutenants,â Blackstone continued. âYouâd have been annoyed, certainly. Youâd have torn a strip off him, undoubtedly. You may even have put him on some kind of punishment parade. But you wouldnât have felt the rage . And why did you feel it when I helped myself to a drink â because Iâm a jumped-up ex-sergeant who refuses to even call you âsirâ!â
âItâs not as simple as that,â Carstairs mumbled.
âItâs exactly as simple as that,â Blackstone contradicted him. âIf the circumstances are right, anyone can kill anyone. And thatâs why Iâm here â to find out what those circumstances were.â
âI want to make