“Not at all,” said Joe politely. “If he hadn’t taken the steps to preserve it, it would have disappeared with the remainder down the drainage channel on the autopsy table. Some solid evidence at last! May we see?”

The metal box was strong and airtight and Joe struggled to get it open.

“Lord, what a pong!” Hunnyton exclaimed as Joe removed the lid.

“It’s not Sachertorte, I think we’d all agree,” Adelaide said, wrinkling her nose.

Joe poked at the contents with a pencil end. “But it is cake. Was cake. It looks more like the sweepings of an ancient Egyptian mummy’s tomb. A sop to Cerberus? Some opiate in there, did your father assume? A little something to quieten the horse?”

“You’ll need to take it to a laboratory in Cambridge if you want to find out. My father’s equipment was not up to the job. But I’ll tell you something. Pa’s not easily put off. He decided that if the cake was laced with something mysterious intended for use on the horse, it was probably acquired from the chemist. He went along and grilled old Mr. Morrison. Made him show his dispensing book.” Her eyes gleamed and she said apologetically, “No right to do that, I’m sure you’d be the first to tell him, but Pa can be very forceful and the local … country shyness”—she looked with smiling apology at Hunnyton—“ ‘foot shuffling’ he calls it—irritates him no end. Faced with all that ‘Don’t you be asking me, sir, twern’t none o’ my business,’ stuff he turns into a raging bully. Interesting, what he managed to extract, though. And no illegalities revealed, so no harm done. The day before the adventure, our innocent chemist had sold four bags of exotic culinary spices. To Grace Aldred, Lavinia’s maid.” She handed over a sheet of paper. “He took a copy: fenugreek, cumin, rosemary, cinnamon. Grace told him the cook had requested them to make up a curry.”

“Sounds reasonable to me. Not sure about the rosemary,” Joe said, “but the others are all constituents of Indian dishes. They do, however, as I think you’ve guessed, have another quite different use.” He looked at Hunnyton, who understood the unspoken question and nodded imperceptibly.

The superintendent undertook the explanation. “Horse magic! In folklore, those spices are all attractants. Horses have huge nostrils and a very sensitive sense of smell. If you want a horse to love you or just behave itself in your presence you can do it by magicking it with these scents, which it adores.” He grinned. “They tell me oil of cloves dabbed on a hanky works a treat too.”

“That’s the refined way of doing it,” Adelaide said. “My father came upon a ploughman once, stripped to his skin in the shed, in the act of wiping down his armpits with a bit of stale bread. When Pa challenged him on his strange behaviour, he explained that he was taking on a new horse. This sweat business was a good way, known to all the horsemen, of making horses familiar with their handler’s scent.” She wrinkled her nose. “I must say, this bit of cake smells as though it’s been somewhere even less salubrious than a ploughman’s armpit at close of play on Plough Sunday.”

Joe picked up the box, looked more closely, held it to his nose and inhaled deeply. For a moment his head reeled and his stomach churned. He couldn’t quite smother an exclamation of distress so visceral the other two turned a gaze of solicitous enquiry on him. He put the lid back on firmly and, gasping apologetically through gritted teeth, recalled: “Trenches. Pinned down. Holed up unable to clear out for a fortnight. Plague of rats feasting on the bodies we couldn’t dispose of. The men bayoneted them. Left them lying about in piles to rot. Same smell.” He stabbed an accusing finger at the silver box. “Rotten rat carcass. It’s the livers that go first … the stinkiest bit … Excuse me …”

Joe dashed from the room and, thankful that the front door had been left open, he made his way quickly to the nearest rose bed. Through his unpleasant retching noises, he was aware of a clattering of clogs down the hallway. A moment later, a white cotton handkerchief was pushed over his nose.

“Lavender. Breathe it in. Antidote.”

A cool, professional hand ran lightly over his forehead. A warm, very unprofessional voice murmured in his ear, “That’ll teach you to go sticking that great conk of yours into unknown substances. Poisons can be inhaled, you know. But I don’t think it’s poison that’s provoked this reaction. It’s memory. Smell and taste—they can be very acute and the mind associates them with pleasure or pain we’ve experienced in the past. This is very real nausea you’re suffering but the brain will soon sound the all-clear and you’ll wonder what on earth that was all about. I’m sure you needn’t worry.”

“Embarrassing, though! What do you prescribe, Doctor?” Joe managed to say, beginning to win the struggle with his heaving stomach.

“Keep starching the old upper lip and stay away from dead rats, of course. Ready to come back inside? Your friend is anxious.”

Hunnyton was standing by with a glass of water when they rejoined him.

Adelaide exchanged a meaningful look with him and voiced the thoughts of both of them. “Just imagine, Superintendent—if it can do that to him—what must it have done for an animal with a hundred times the sensitivity?”

“Terrified the poor beast to death,” said Hunnyton. “I think we understand now after that little demonstration. Is the commissioner all right?” He peered at Joe with concern. “Looks a bit seedy to me … Now listen. There’s not many who know and I ought not to be speaking out, but … oh, well. We all accept that it’s fear and its response, flight, that dominate in a horse? Fear is what’s kept the species alive through the millions of years they’ve been on earth.” Joe and Adelaide nodded. “Man has always tried to influence and tame horses to fulfil his own requirements. He’s worked out some subtle ways of doing that. There’s horse lure, like the curry spices, and then there’s horse bate. Nasty stuff that has the opposite effect. Smear a trace of it on the posts of a horse’s stall and it won’t pass between them even if it’s starving. Push a load of it on a bun close up to its nostrils and you’d send it out of its mind. Do that when you’re advancing on it in a narrow space, driving it backwards, blocking its escape route, and, mad with fear, it’s going to tear right through you. As its nature insists. It has no choice.”

“Bate, you say? What is ‘bate’? Superintendent, what exactly do you think was smeared on that piece of cake?” Adelaide asked. “What’s the commissioner just breathed into his lungs? I insist on hearing.”

“Decayed stoat liver, steeped until rancid in rabbit’s blood and cat’s urine, then dried out. Most likely,” he said with relish.

“You can’t get that off the shelf at Mr. Harrison’s,” Adelaide said. “And how on earth do you get a cat to pee in a pot?”

“Well, lacking a cooperative moggie, horse’s urine is more plentiful and does the job.”

“You’re having me on!”

“No indeed. Believe me—this is serious magic! Produced locally, I’d say, to an ages-old recipe by someone with the knowledge. The Horse Knowledge.”

“It sounds like hogwash to me,” Adelaide said crisply. “Well, no, that’s about the one ingredient that didn’t feature in your little confection. Why do people think they need to have recourse to magic potions? My father’s been handling horses all his working life without benefit of fenugreek and cumin. Rabbit’s blood and stoat’s liver have never featured in his materia medica.”

“Oh, I don’t know. Horses hate stoats, even the live ones,” Joe remarked. “The sight and smell of one on the road will send them into paroxysms of fear or fury—you must have noticed?”

“We certainly didn’t miss the paroxysms in the rose bed, I’ll grant you that,” she said thoughtfully and summed up for herself: “So, Lavinia bought the lure from Mr. Harrison, helped herself to a bun from the tea table and gave it a very special frosting. It’s this she must have thought she was using when she went down to the stable to make her overtures to young Lucifer. But somewhere along the way—where? and when?—the sweet spiced cake was … exchanged?—for a piece that had been ‘bated’ with a substance obnoxious and threatening to the horse. Am I getting this right?”