Watson reached for the knife, grasping until his fingers closed over it, and not looking, slid it through the butter, and began to spread it upon his toast. "There was quite a stir last night, Holmes," He called into the parlor as he scanned the column. "Two inmates killed in solitary confinement, and neither of them even had a weapon…" Holmes replied, inquiring after the presence of guards, and Watson raised the toast to eat, but instead of the action ending in a satisfying crunch, it ended in an enraged shriek: "HOLMES, WHY IS THERE A BLOODY KNIFE WHERE THE BUTTER KNIFE SHOULD BE?"

He cried in triumph: "Ah, that's where I misplaced it!"

My answer to the unnamed crime relic in the butter dish.