*Have you ever used it?'

*No.'

*Or cut yourself with it?'

*No.'

*Have any customers touched it?'

*No.'

*You are certain of that?' Sidney Grice was rattling out the questions so fast that William Ashby hardly had time to answer.

*Yes.'

*Did your wife ever touch it a to polish it, for example?'

*No. I looked after the knife cabinet. She did not like it.'

Inspector Pound turned the knife over.

*Looks clean.'

*Do not touch the blade,' Sidney Grice said, and turned back to William Ashby. *So you are willing to swear that this blade has never had any blood on it whilst it has been in your possession?'

William Ashby looked him straight in the eye. *On my life, Mr Grice.' And Sidney Grice smiled coldly. *Your life may well depend upon it, Mr Ashby.' He picked up the knife again and said to the constable, *I shall need a clean bowl of clean water.'

The constable looked uncertain.

*Well, see to it, man.' Inspector Pound clicked his fingers and the constable hurried out. *What is your game, Mr Grice?'

*You know my interest in science, Inspector,' my guardian said. *Well, there is a certain professor of pharmacology at the University College by the name of Cornelius Latingate, and he has devised a chemical a.n.a.lysis which is specific to the presence of haemoglobin.'

*I'm sorry, Mr Grice,' William Ashby said, *but you have lost me.'

*It is a test for blood.' Sidney Grice took his watch out but did not open it, making it spin on its chain and swing side to side. *It can detect the presence of blood on an apparently clean surface or material for up to five days after it has been put there. Imagine finding a bloodstained garment, for example. The owner of that garment insists it is paint. This test can verify or refute his story. The older tests only detected iron, and would show positive reactions to blood and rust. This test detects a protein present only in blood and is so sensitive that it will demonstrate a drop so small as to be invisible to the naked eye.'

*But if I had killed my wife with that knife why would I put it back on display?' William Ashby asked.

*Who said it was on display?' Sidney Grice jumped in.

*It was in my cabinet.'

*Was it?'

*I know it was, that very day, because I took out all the knives and polished them,' William Ashby said.

*But was it in the cabinet after the murder?'

*I suppose it was. I did not check.'

*Your wife was killed with a knife with a blade shaped like this, Mr Ashby.'

William Ashby sat up and said, *Then it must have been him.'

*Why would an Italian stranger murder your wife?'

*I have no idea.'

*Why would he behave in such an ostentatious manner? It could only be to make sure that you remembered him.' Sidney Grice stopped his watch spinning and peered at the back of it.

*I don't know.'

*Rivincita means revenge. It was written on the wall in your wife's blood.'

*No.' William Ashby swept the mug on to the floor. *You are just saying these things to torment me.' He stood up.

*It is true,' I said, and the prisoner put his hand to his mouth.

*Sit down, Ashby.' Inspector Pound stepped towards him and William Ashby sank back on to his chair, breathing fast.

*Why would an Italian want revenge upon your wife?' Sidney Grice slipped the watch back into his waistcoat.

*I don't know, Mr Grice.'

*Did she or you have any Italian friends or enemies?'

*No.'

*Any Italian ancestry or connections of any kind?'

*Not that I know of.' William Ashby put his hands down, trying to calm himself. *I don't know who he was or why he did what he did, but I do know one thing, Mr Grice. There is a madman on the loose and he must be found immediately before he murders some other poor woman and, when he does, will you accuse her poor husband too?'

The door opened.

*If your knife fails the test, then I shall follow your unlikely lead,' Sidney Grice said as the constable returned, carrying a white-enamelled basin and placing it very carefully on the table.

*You took your time,' Sidney Grice told him.

*Sorry, sir, but there wasn't a bowl in the station.'

Sidney Grice touched it and flinched. *The water is near frozen.'

He produced a blue bottle with a handwritten label on it from his bag and tipped a few white crystals into the basin.

*Observe,' he said, *how clear the solution is.'

We all stood to watch.

*Now,' Sidney Grice said, *observe what happens if I take this knife and swirl it around the solution to wash any possible residue off it. See that? It has turned red. There is no doubt about it. This knife has been in contact with blood within the last few days.'

*But that is not possible.' William Ashby looked bewildered.

*There is no doubt about it,' Sidney Grice said, and William Ashby sat down suddenly and ran his fingers over his brow.

*I remember now,' he said. *I nicked myself when I wiped it.'

*Show me the cut.'

*It was very small.'

*It was deep enough to bleed so it cannot have healed yet.'

William Ashby looked at us both and inhaled deeply, and said, *I do not know how, Mr Grice, but you have put a noose round my neck.'

*How did that knife get blood on it?' Sidney Grice asked, but William Ashby lowered his head and did not reply.

*I am d.a.m.ned,' he said at last.

*So you are,' Sidney Grice said and snapped his notebook shut.

16.

The Red Book *I will see you out, Mr Grice,' Inspector Pound said, and we pushed back our chairs. *Take him back to the cell, Constable.'

William Ashby did not look at us as we left, though I looked back at him, climbing to his feet, a crumpled man.

*Come into my office.' Inspector Pound led us into an even smaller room, the desk piled high with ma.n.u.scripts and red-bound volumes. *I cannot offer you a seat.' The one chair was overflowing with more papers. *I could take a year to sort through the paperwork that my superiors expect me to do and let a thousand murderers, housebreakers and pickpockets run free.' He leaned back on the edge of the desk. *Well, that was a pretty experiment, Mr Grice. Are you sure it is foolproof? Something like that will swing a case, but we will not look very clever if the defence can show that your crystals change colour with strawberry jam.'

He toed a ball of paper under the desk.

*Professor Latingate will back us all the way.' Sidney Grice leaned his shoulder against the wall. *He is a good performer in the witness box. Juries are impressed by academic t.i.tles and he can show them enough chemical charts to convince them he knows what he is talking about. I have seen him demonstrate his test to an audience of fellow scientists who were invited to bring whatever substances they thought might change the colour of the crystals, and not one of them succeeded.'

*Funny.' Inspector Pound frowned. *I would have bet my liver on him being innocent.'

Sidney Grice snorted and said, *Ashby knew he had been caught out. He said as much.'

*I do not think he did,' I said. *I think he was dumbfounded. He did not know how to counter your science.'

*Mr Grice has never been wrong yet,' Inspector Pound told me. *Why, we had Gertrude Rayment, the Lambeth Poisoner, walking free before he was able to prove that she had reset her grandmother clock to concoct an alibi.'

*It is not only the test that shows his guilt,' Sidney Grice said. *It is the whole gamut of inconsistencies in his version of events that condemn him.'

*How so?' I tried not to show my loathing of his smugness.

Sidney Grice gave his little smile. *If we are to believe Ashby's account of events, a preposterous Italian man came into his shop and flamboyantly purchased the very weapon with which he intended to murder the lady of the house a couple of weeks later.'

*But why would he make that story up?' I asked.

*To send us on a wild goose chase for somebody we could never find because he never existed.' Sidney Grice measured his words for my poor brain. *He was doubtless hoping to make us think the Slurry Street murderer was on the prowl again.'

*If that rumour was circulated there would be ma.s.s panic.' The inspector picked up a red book and stuffed it on to a shelf. *Which is another good reason to discount it.'

Another book fell dully off the end of the shelf and he booted it under his desk.

*What about the writing in blood?' I asked. *Rivincita.'

Inspector Pound shrugged. *The sewer press claimed that was smeared on the walls in Slurry Street, but I never saw it.'

*But it seems such an unlikely story to make up,' I said. *Who would believe it?'

*If a story is unlikely, then it is unlikely to be true,' Inspector Pound said. *Surely even a girl can see the sense of that.'

*If a story is unlikely to be made up, then it is likely to be true,' I said. *Surely even a man can grasp that logic.'

The inspector puffed and said, *You should hear some of the tales we get. We had a man yesterday who said that all the stolen goods in his cellar were put there by a man from the moon. An Italian is a little easier to believe than that.'

Sidney Grice waved his hand irritably and said, *Next we are expected to believe that he sat in an uncomfortable chair fast asleep while this fellow opened his back door.'

*Why the back door?' Inspector Pound asked.

*Because there are muddy footprints in the yard to the door, which stop at the threshold, and because he claims that the shop bell only sounded once,' Sidney Grice said. *So this fabulous Italian let a cold draught and the outside noise in, took off his boots, crept past, opened a squeaky door and murdered Sarah Ashby without Mr Ashby even stirring.'

*If he were lying, surely he would have pretended to be a heavy sleeper,' I said.

*His mother-in-law had already gainsaid him,' Sidney Grice said, *and, though he could not have known that, he knew she would in court. Also, the match girl, who was well-disposed to Ashby and ill-disposed to his wife and so may be tempted to corroborate his story, has already told us that n.o.body entered or left the shop for some hours before he raised the alarm.'

*And why would his wife be in her bare feet if she were working in the shop?' Inspector Pound said.

*Precisely.' Sidney Grice jabbed the air with his forefinger. *I have examined her feet and, although she had a bruise, they were clean and soft with no splinters in them. The shop floor is rough and unplaned.'

*But he is so gentle,' I said.

*He was a soldier,' my guardian reminded me. *Soldiers shoot and bayonet people for a living. How gentle an occupation is that?'

*I still do not believe it.'

*There are a few loose ends,' Sidney Grice said, *but I have no doubt that I shall be able to tie them together. Why do you think I offered the prisoner my mug of tea?'

*Because you did not like it,' I answered.