This appears as Murder, My Sweet, on Letterboxd, TMDB, and IMDb, but is actually Farewell, My Lovely. Apparently it was re-titled for the US market back in 1944, because there was a musical with the original name.

The original being, of course, one of Raymond Chandler's novels about the private detective Philip Marlowe. This is a really good adaptation, with what sounds like most of Chandler's dialogue (I mean, why would you change it?).

It's proper, classic noir. But/and there's a scene where Marlowe is captured by the bad guys, drugged, and interrogated, that feels more like the mind-control paranoia of sixties films like The Ipcress File. The visual ideas for suggesting that kind of thing go back a long way, obviously.