get to the bottom

『007/スペクター』に関する記事から取り上げます。
The story sees Bond learn of the existence of an international terrorist group while his boss, M (now played by Ralph Fiennes), deals with political infighting at Britain’s Joint Intelligence Service — a merged MI5 and MI6. Agent 007 goes off the grid to get to the bottom of who’s behind the group, SPECTRE, and when he finds Oberhauser at the helm Bond soon learns the villain is not who he seems to be.
Craig says he admires Waltz’s ability to “spontaneously produce a new mood or new expression that says so much. He’s very inventive, and can go from nice to rotten and be convincing in both. As a person, he’s a good guy, and it’s good he’s not stereotyped as the smirking villain you root against.”
http://www.japantimes.co.jp/culture/2015/12/03/films/james-bond-deals-old-ghosts-spectre/#.VmCSpTihdMv

ここで取り上げるのは “get to the bottom”です。LDOCEでは “to find out the cause of a problem or situation”と定義されています。さらに、この “bottom”は『ジーニアス英和辞典第4版（大修館書店）』では「（物事の）本質、真相；裏面、黒幕」とありました。例として “get to the bottom”は「真相をつかむ」が挙がっていますが、ここでは「ボンドは国際犯罪組織スペクターの黒幕をつきとめていく」という意味であると考えられます。（Inaho）