Holmes examined it with interest.

“Where did you get it?”

“There is a central heating furnace in the cellar under Lady Beatrice’s room. It’s been off for some time, but Sir Robert complained of cold and had it on again.

“Harvey runs it⁠—he’s one of my lads. This very morning he came to me with this which he found raking out the cinders. He didn’t like the look of it.”

“Nor do I,” said Holmes. “What do you make of it, Watson?”

It was burned to a black cinder, but there could be no question as to its anatomical significance.

“It’s the upper condyle of a human femur,” said I.

“Exactly!” Holmes had become very serious. “When does this lad tend to the furnace?”

“He makes it up every evening and then leaves it.”