“No, I shouldn’t,” said Thaddeus “we’ll pass you off as a business acquaintance of mine up from town, and you can stay all night and watch developments.”

So it was arranged.  The detective was introduced into the family as a correspondent of Thaddeus’s firm, and he settled down to watch the household.  Afternoon and evening went by without developments, and at about eleven o’clock every light in the house was extinguished, and the whole family, from the head of the house to the cook, had apparently retired.

At half-past eleven, however, there were decided signs of life within the walls of Thaddeus’s home.  The clew was working satisfactorily, and the complete revelation of the mystery was close at hand.

The remainder of the narrative can best be told in the words of the detective: 

“When Mr. Perkins sent for me,” he said, “and told me all that had happened, I made up my mind that he had a servant in his house for whom the police had been on the lookout for some time.  I thought she was a certain Helen Malony, alias Bridget O’Shaughnessy, alias many other names, who was nothing more nor less than the agent of a clever band of thieves who had lifted thousands of dollars of swag in the line of household silver, valuable books, diamonds, and other things from private houses, where she had been employed in various capacities.  I could not understand why she should have made ’way with the dishes and Mrs. Perkins’s table-cloth, but there’s no accounting for tastes of people in that line of business, so I didn’t bother much trying to reason that matter out.

“After we’d had dinner and spent the evening in Mr. Perkins’s library, the family went to bed, and I pretended to do the same.  Instead of really going to bed, I waited my chance and slipped down the stairs into the dining-room, and got under the table.  At eleven o’clock the maidservants went up to their rooms, and at quarter-past there wasn’t a light burning in the house.  I sat there in the dining-room waiting, and just as the clock struck half-past eleven I heard a noise out on the stairs, and in less than half a minute a sulphur match was struck almost over my head under the table, and there stood the cook, her face livid as that of a dead person, and in her hand she held a candle, which she lit with the match.  From where I was I could see everything she did, which was not much.  She simply gathered up all the table fixings she could, and started down-stairs into the kitchen with ’em.  Then I went up to Mr. Perkins’s room and called him.  He put on his clothes and got out his revolver, when we stole down-stairs together, leaving Mrs. Perkins up-stairs, with her boy’s nurse and the waitress to keep her company.

“In a second we were in the laundry, which was as dark as the ace of spades, except where the light from four gas-jets in the kitchen streamed in through the half-open door.  Mr. Perkins was for pouncing in on the cook at once, but I was after the rest of the gang as much as I was for the cook, and I persuaded him to wait; and, by thunder, we were paid for waiting.  It was the queerest case I ever had.