“My conclusions precisely,” said Holmes. “Let us get the body upstairs now, before the women return.”

Between us, we carried the body of poor Jack Prentice upstairs and laid him out on the tap-room floor, covered in an old dust sheet we found in a cupboard.

“What made you suspect that Prentice’s body might be down in the cellar?” I asked Holmes.

“The door to the street, Watson. Mrs Prentice found it unlocked on Tuesday morning, and it was supposed that Prentice had risen and gone out early. But at the time he was supposed to have left, the night would still have been pitch black. I could not believe that he would have left the door to the street unlocked when it was dark and the other occupants of the house were still asleep in bed upstairs. He would instead have locked the door on the outside and taken the key with him, knowing that there was a spare key behind the bar which his wife could use. It was possible, of course, that Prentice had been taken from the house by force, but it was equally possible that he had never left the building at all, and that the door was unlocked simply because he had never got round to locking it the night before. And if – dead or alive – he was still here, the cellar seemed the likeliest place to find him. That was the hypothesis I wished to test.”

At that moment, there came the sound of a key being inserted in the lock, and a moment later we were joined by Mrs Prentice and Maria. There was a moment of dreadful silence, as they saw the shrouded figure on the floor, and the blood seemed to drain from their faces.

Holmes took a step forward and addressed Mrs Prentice. “I am afraid you must prepare yourself for bad news,” said he, at which Mrs Prentice put down her shopping basket and began sobbing, leaning for support on the younger woman, who put her arm round her. Then, after a moment, she gathered herself together and stepped forward to identify the dead man. Inspector Jones lifted the shroud, at which she nodded her head and began to weep copiously. I brought forward a chair and sat her down on it, then went behind the bar to find some brandy.

“Who could have done such a thing?” the poor woman wailed, “and why?”

“Have no fear, madam,” said Jones in a reassuring tone. “We shall catch whoever committed this terrible crime. He shall not escape us!”

“The ‘why’,” said Holmes in a grim voice, “is because of this list that Jack was writing the last time you saw him alive.” He took the sheet of paper from his pocket and unfolded it. “He was certainly trying to work something out, but it was not the value of the ring that you saw. He was using Roman numerals so that you would not guess what he was writing, for it was something he was ashamed of, and he did not want to lose your trust, which I believe he valued above all else.”

“But what was it he was working out?” asked Mrs Prentice in a puzzled tone as I handed her a tot of brandy.

“I believe he was calculating dates,” said Holmes. “When I got home last night and examined this sheet anew, it seemed to me then that there was perhaps a slightly wider space after the third numeral on each line, and I conjectured that what he was writing in this deliberately cryptic fashion was perhaps a seven, followed by different numbers of single strokes, indicating ‘seventy-four’, ‘seventy-three’, ‘seventy-two’ and so on. This in turn suggests the years known by those abbreviations. If this is so, then the other letters must surely be the initials of the European ports that he remembered visiting in those years – Amsterdam, Hamburg, Oporto, Lisbon and so on. That is the only explanation that makes sense.”

“But why should he be trying to remember what he was doing all that time ago?” asked Mrs Prentice. “Those days were before he served his time in Pentonville; and after he came out, he gave up the sea completely. That’s all just ancient history now.”

“It might not be simply ancient history to everyone,” returned Holmes.

“What do you mean?”

“To someone who was born then, for instance, one of those years would undeniably be a significant date. Someone such as Maria, perhaps.” He turned to the Spanish girl as he spoke, and she took a step backwards, a look of alarm on her face.

“I do not understand!” she cried.

“I think you do,” returned Holmes. “I think you showed Jack Prentice that amethyst ring – a ring he had perhaps given to some woman he met in Corunna at a time when he was feeling fairly well-off from his ill-gotten gains – and you accused him of being your father. That is why I believe he was so concerned to recall everywhere he had been in those years of the early ’70s.”

“You lie!” cried Maria.

“I think not,” said Holmes. “You are the one that lied. There is no ‘C’ on Jack Prentice’s list – ‘C’ for Corunna – until ’74, which is much too late for him to have been your father. I believe you were down here in hiding, late on Monday evening, when Mrs Prentice came downstairs to see what was happening. After she had gone back upstairs, Prentice, who had satisfied himself that he could not possibly be your father, confronted you and demanded to know, I imagine, what sort of a trick you were trying to play on him. In the ensuing quarrel, you seized the candlestick from the mantelpiece and struck him with it. You may not have intended to kill him, but that was the result. You then dragged his body down the cellar steps, and across the cellar floor. Your footsteps were quite clear in the dust down there.”

“Lies! All lies!” cried the girl.

“If I am right,” continued Holmes, turning to Inspector Jones, “she’s probably got the ring on her. It’s certainly not in any of Prentice’s pockets. I suggest she be searched.”

“I have no ring!” the girl protested. “I never have ring!”

“That’s not true, Maria,” said Mrs Prentice in a quiet tone. “I saw you fiddling with a ring one day last week, but I never saw what it was.”

“All right,” said Maria. “I have ring. I find it on floor.”

“Let us see it, then,” said Jones.

She stepped forward in a reluctant fashion and put her hand in her coat pocket. The next moment a dreadful thing happened. She took her hand from her pocket, but in it was not the ring we were all expecting to see, but a wicked-looking little dagger with a narrow, pointed blade. In that same instant, with a loud howl of rage, she flung herself forward at Sherlock Holmes, the dagger aimed for his breast. But quick though she was, Holmes was quicker. His hand shot out like lightning, seized her wrist and held it tightly, then he pressed her arm down and forced her to drop the knife. At that point she let out an ear-piercing scream and began to kick him violently on the shins, at the same time lunging forward to try to bite him. Jones and I sprang forward and pulled her away, and in a moment the policeman had clapped a pair of handcuffs on her. At that moment the door opened and Constable Griffin put his head in to enquire if everything was all right.

“There’s a young woman outside, sir,” he added, “who wants to come in – name of Lily Bates.”

“That’s my daughter,” cried Mrs Prentice, rising to her feet. A moment later, a sandy-haired young woman pushed her way past the police constable and into the room. “Lily!” cried Mrs Prentice in a voice full of emotion. “Your father is dead!” The two women embraced, and in a few words Mrs Prentice gave her daughter a brief account of what had happened.

The younger woman’s eyes flashed fire. “I knew it!” she cried, looking with anger at the Spanish girl. “I always thought she was a scheming little minx! You do know, Ma, that she’s the reason William stopped coming round here. He didn’t trust her. He always said she was no good and was up to something!”

“Here’s a ring!” said Jones, who had been feeling in the Spanish girl’s coat pockets. “Would you say that that is an amethyst, Mr Holmes?” he asked, holding up the ring, which contained a single large purplish stone. Holmes nodded his head, and Mrs Prentice confirmed that it was the ring she had seen her husband slip into his waistcoat pocket on Monday evening.