Just looking at the time factor … there’s Steve’s Holmes up front but a bit short for the slot right now, there’s a second Holmes I also saved, there are plenty of 50s sci-fis but one I’ve held in abeyance for a while is this police procedural, loosely based on Capone. One review said it was more accurate than The Untouchables.
Positives are the two leads, the reasonable story, the way it was a classic crime flick, the sharp copy. Negatives are mainly around the plodding nature of the plot but I quite liked it.
https://en.wikipedia.org/wiki/The_Undercover_Man