“Yes, the ally!” repeated Holmes, pensively. “There are features of interest about this ally. He lifts the case from the regions of the commonplace. I fancy that this ally breaks fresh ground in the annals of crime in this country⁠—though parallel cases suggest themselves from India, and, if my memory serves me, from Senegambia.”

“How came he, then?” I reiterated. “The door is locked, the window is inaccessible. Was it through the chimney?”

“The grate is much too small,” he answered. “I had already considered that possibility.”

“How then?” I persisted.