caper

東野圭吾の "The Devotion of Suspect X" を読んでいます。
"We did spend a lot of time and manpower questioning people around the station here. If your theory's right, that was all wasted time."
"Not a waste, per se. After all, the bicycle was stolen from her. But I don't think this case is simple enough that knowing that fact will do you any good at all. No, our littel caper was constructed far more craftily and with greater precision than that."
"caper" と言うと西洋料理に添え物（特にスモークサーモンには必ず付く）として出て来る見かけは小さな豆のような、食感は独特で豆ではないと直ぐに分かりますが、食べ物を思い浮かべますが、上記の "caper" 当然別物です。辞書を見ます。
・Oxford English Dictionary: An activity or escapade, typically one that is illicit or ridiculous.: Now he may face the full 10 years, plus punishment for the grave-robbing caper.

・Collins Dictionary: A dishonest or illegal activity can be referred to as a caper.; She served six months in prison for the helicopter caper.

・Cambridge English Dictionary: an illegal, unusual, or entertaining activity: The whole incident started as an innocent caper.
なるほどここでは死体発見場所の近くに残されていた自転車盗難事件のことですね。