What was that story?

villainny is looking for stories with knife-kink in them.

And -- does anybody remember a story with a blindfold and a knife, and afterwards when the heat of the moment is over, the "knife" turns out to have been a spoon? I thought it was a Due South story, but I can't remember which one it was.

Does anyone else remember this, or am I making it up?

Edit: auster found it! Sentinel, actually, not Due South. On Edge by Shadow.