In the summer of 189… I succeeded in accomplishing the impossible and finally convinced Holmes to take a holiday. He rarely succumbed to such coaxing; last time we weren't able to spend even a week in peace and quiet, and it all ended by the unmasking of the senior and junior Cunninghams. This time, we were guests in a very quiet Buckinghamshire village, staying at the house of my colleague Dr. Stevens, whom I knew from the time of my service in Afghanistan. Edward had no affinity to adventures and devoted his spare time to breeding bees, and therefore I thought that Holmes would not be bored, since recently he has begun to evince interest towards these creatures and even declared that he would like to get more closely acquainted with them, at some point.
We spent the week at a measured pace, taking long walks through the fields during the days and listening to Edward's tales in the evenings. Our neighbours in the village were unobtrusive and did not intrude upon our solitude; occasionally, the apothecary came, who prepared medications according to my colleague's prescriptions, and the parish priest, who once invited us to take a look at the half-decayed Roman chapel, which stood in the overgrown garden near the church.
The next morning, Holmes went for a walk by himself, since I volunteered to help Edward edit his article for "The Lancet", and we spent several hours working on it in the library. Around noon, Edward looked out the window, smiled and remarked,
"It looks like Mr. Holmes found some company."
I glanced outside and saw Holmes talking to a girl of five or six years of age, wearing a yellow dress. My friend's face expressed extreme seriousness and interest in his companion's conversation. She was spreading her hands apart, showing something, without a doubt, huge and amazing, and confirmed her words with energetic nods.
Having heard her, Holmes said a few words to her, which made the girl's face light up with a smile, and shook her hand.
"What were you and Agnes talking about?" I inquired over lunch. Edward had explained that she is the daughter of a greengrocer who lives near the church.
"Oh, she is a very observant young lady," Holmes replied. "She believes that a dragon recently took residence in the village."
"Is that so?" asked Edward, smiling.
"Quite so," my friend confirmed. "She hadn't seen the dragon itself, but she knows that its lair is in the ruined chapel. She had heard something hissing and bubbling there, and one time she even saw the flames."
"And was the dragon huge?" asked I, remembering Agnes' gestures.
"Considering the still short height of Agnes herself, I would say not very huge, no higher or larger than you, Watson."
We laughed, and the conversation drifted to other topics, although Holmes remained pensive for some time.
The next day we returned from our walk to the lake rather late, and it was after dinner that Edward, as if he just remembered it, said,
"Incidentally, I paid a visit to your acquaintance today, Mr Holmes."
"She's not ill, is she?" I inquired.
"No, Agnes is her usual merry and carefree self; I was paying a visit to her older brother. Richard has developed a bad cough which he's had for the last several days. It's rather strange, there seems to be no way to catch a cold in such fine weather as we've been having. And the son of Mr Baggs, our apothecary, is having the same symptoms."
Holmes looked at Edward closely, but said nothing.
"What did you prescribe for them?" asked I, to fill the prolonged pause that fell.
"A cough syrup, as usual. Told them to rest for a couple of days. By the way, Agnes caught up with me in the street just after I left the house, and asked me to convey a message to you, Mr Holmes."
"What was the message?" he asked, leaning forward, his voice clipped.
Edward shrugged his shoulders bemusedly.
"That the hortensias there used to be white, and have now become pink."
We were supposed to leave for home the next day on the 12:30 train, and I intended to discuss with Edward his plans for coming to London this winter, but Holmes dragged me away from the table before I even finished my breakfast, and declared that he wanted to walk around one more time.
I prepared myself for a long walk around the hills, but instead, he led me to the church, saying,
"I seem to recall the priest inviting us to look at the chapel, my dear fellow."
"You have never had the slightest interest in architecture."
"True, but I decided to make an exception."
"And it was Agnes' fanciful tale that inspired you to do so?"
Holmes smiled briefly, but it was obvious that his thoughts were on something else.
The chapel was not remarkable in any way whatsoever. The stone masonry was well-preserved, but the doors were gone and the inside was quite deserted. Perhaps the chapel was used to store something at an earlier time, because wood chips, lumps of dirt, and a few rags were strewn about on the floor.
Holmes strolled around the chapel, looking at the ground attentively, ran his hand around the window-frame, looked out and remarked,
"There are indeed many pink hortensias here. It is too bad that nobody takes care of them. Let's go, Watson, we now have one more errand."
In the village, Holmes stopped at the apothecary's and asked if he has concentrated sulfuric acid, which was urgently needed for an experiment. Grunting, Mr Baggs climbed up the stepladder to the topmost shelf of the case and pulled out a small dark glass bottle from the furthermost corner.
"I've had this bottle for goodness knows how long," he said. "They usually send it to me already diluted."
Holmes thanked him and once we were outside, asked me,
"Watson, I have a few more visits to make. Go to the station without me. I will say our farewells to Mr Stevens and will come before the train leaves."
I attempted to protest, but he assured me that this was important, and swiftly departed.
Holmes appeared a few minutes before the train was due to leave. The right sleeve of his jacket was covered by dust, and a pink hortensia adorned his buttonhole.
"So," said he merrily, rubbing his hands, "you have succeeded, my dear Watson! You compelled me to rest, but the holiday did not seem a whit boring to me, although for that, we must thank not so much the local sights, but Agnes, whose riddle I solved."
"Case of the dragon?" asked I, failing to hold back my laughter.
"A good title for a story," Holmes responded seriously, "but everything is somewhat more prosaic and dangerous."
He leaned back in his seat.
"I'm afraid that I disagreed with Agnes' belief in the dragon from the beginning. I thought it was just children playing inside the chapel. But when Mr Stevens told us about the cough which befell two boys without the slightest cause for it, and then gave me Agnes' message, I was struck by a deduction."
"I have done many chemical experiments, Watson, and I know how carefully one must conduct them so as not to poison or burn oneself. A bad cough is one of the typical symptoms of sulfuric acid poisoning, if one inhales the acid vapours even for a brief time. The friend of Agnes' brother is an apothecary's son, he could get a hold of sulfuric acid. Putting that fact together with the hissing and bubbling that Agnes had heard, I came to the conclusion that the boys were conducting experiments in the chapel. To make certain, I took you there. I found traces of a fire, and also the traces of lime and several small lumps of clay. Clay reacts with sulfuric acid to yield aluminum sulfate, that's one of the simplest chemical experiments one can do."
"And the pink hortensias?"
"That's a side effect. I had to resort to cunning and to Agnes' help so as to speak to her brother, and he confessed that they had started conducting experiments several months ago, first with things they had at hand, and the unused lime they tossed out the window, so as to cover their traces. If you add lime to the soil, the petals of hortensias become pink. That trick has been long known to the gardeners, but our young chemists achieved it through ignorance."
"Is that why you bought some sulfuric acid from Mr Baggs?"
"Yes, to test my suspicions. He is the only person except our friend who possesses chemicals in this village, and it is doubtful that he frequently has occasion to use the concentrated sulfuric acid, if he is usually sent the dilute one for the prescriptions. The bottle turned out to contain oil. No doubt Mr Baggs would have discovered it sometime, but not anytime soon."
"So what did you do with Agnes' brother?"
"I gave him a detailed lecture about poisons and told him how to handle acids," replied Holmes, his eyes gleaming. "It would be foolish to restrict his passion for science."
"And is this your fee?" I asked, pointing to the hortensia.
Holmes took the flower out of his buttonhole and held it up to the window.
"I suppose so. And it's quite a significant fee."