I made one last brief visit to Tillyfor’s apartment, many weeks after the rest of the affair had been settled, or at least on its way to being decently forgotten by almost everybody. I made the familiar way to her door and knocked briskly, resisting the temptation to light another cigarette while I waited. After a short while, she opened the door a crack, as cautiously as ever, her eyes widening as she realised it was I standing there.
"Findo! What are you doing here?" she demanded, throwing back the door more than wide enough for me to come inside.
"I’m delighted to say I've finally located your missing sister," I announced calmly.
"Tillykerie!" Tillyfor shrieked, "She’s back! But where is she?"
She rushed outside, dressed only in her stylish bathrobe and fluffy slippers, looking wildly up and down the paths and staircases.
"Come inside," I advised, "She'll be here in a few minutes. So sit down and try and keep calm while we wait."
I ushered her back inside and gently persuaded her in the direction of a chair. I knew what to expect now and I was pretty certain I could arrange things on a schedule to suit myself.
I had investigated this affair quite carefully. I had spent more effort than I should on door-to-door investigations, cautiously questioning anybody I could persuade to talk to me in the neighbourhood where Tillyfor lived.
One thing which struck me belatedly - very much later than it should have done, if I must be honest - was that the two sisters Tillyfor and Tillykerie were never seen together. Indeed, everything I had been told - even by Tillyfor herself - indicated that only one of the two sisters ever left that tiny apartment at a time.
It seemed I had been looking in the wrong place for a solution for this part of the mystery.
Even now, I still have a few contacts back at the old university where, as a youngster, I had studied criminology, forensics and psychology, and planned on becoming a policeman.
Back then, I was little more than average as a student. I found many of the classes too abstract, too removed from what here I should describe as the Human Condition - or at least the equivalent for Goblins. Exceptionally, the classes in psychology had caught my interest more than most, and I had achieved good enough grades to attract the personal attention of the tutors.
A few days ago, after my door-to-door investigations around Tillyfor’s place, I made a return visit. I had made my way along those familiar corridors of the University facility, glancing nostalgically at the ancient stonework interspersed by heavy oak doors at wide intervals. I found the right door and knocked loudly on the age-darkened wood.
I pushed the door open and stepped inside.
"Professor," I began, "I don't know whether you remember me...?"
"Gask, junior," he said shortly, "I never forget a good student. Come in, close the door, sit down."
The Professor hadn't changed a bit in the many decades since I had last passed this way. He had seemed timelessly ageless back then, when I had presented myself for tutorials. His eyes were just as bright, his puce waistcoat identical, and he was in exactly the same position at his desk as I remembered from all those years ago.
It seemed as if the room furnishings had coalesced around him over the decades. There were hundreds of feet of bookshelves containing his private library. The books themselves showed noticeable signs of both age and hard use; he was not somebody who would merely decorate their walls, but regarded the books as a vital working resource. There was little in the room apart from the books, and his desk and comfortably supportive chair: a few rather worn and lumpy overstuffed seats for visitors - presumably to discourage them from overstaying their welcome - and some lights and a very few framed certificates whose parchment had faded almost to the point of unintelligibility.
I sat up straight in the overstuffed chair the Professor had indicated, and tried to look intelligent.
"So, I understand that you are a Private Investigator now, is that right?"
I nodded dumbly.
"And it is, I surmise, some aspect of a case which has brought you to my door, yes?"
"Yes, Professor." He really was a very intelligent Goblin.
He leaned forward over the desk, steepling his fingers.
"Sounds interesting, if you have thought to bring it to me after all these years. So tell me all about it."
I told him everything I knew, and thought, and suspected, about Tillykerie and Tillyfor, everything I had discovered during the investigation. I left nothing out. There was no point: he was smart enough to spot any deliberate omission on my part, and stubborn enough to refuse to assist if he felt he was being slighted or mislead.
As it turned out, the Professor was very helpful indeed. He explained the basic principles involved and something of the science which lay behind it, and directed me to some very specific textbooks which I later found with ease in the University stacks. With hindsight, it was all so very obvious. My ankle already metaphorically ached where I started kicking myself.
And finally, the Professor directed me to another - very specific - textbook, and an even more specific chapter, which taught me an ancient skill which he thought might allow me to bring matters to a conclusion. It was a skill I was about to try out on Tillyfor this very afternoon.