What's that? "Rem acu tetigisti."

Rem acu tetigisti. From Jeeves in the Morning by P.G. Wodehouse. Conversation between Jeeves and Bertram Wooster.

"Precisely, sir. Rem acu tetigisti."

"Rem ------?"

"Acu tetigisti, sir. A Latin expression. Literally it means 'You have touched the matter with a needle,' but a more idiomatic rendering would be - "

"Put my finger on the nub?"

"Exactly, sir."

"Yes, I get it now. You have clarified the situation. Getting right down to it, these two old buzzards have got to foregather in secret and require a hideout."