‘...believable characters and plot;’
you found the Sidney Greenstreet/Peter Lorre pair believable...?
In my 70 years, from Texas to Hollywood & 'round the world back and back, I have run into more than one set of amoral characters who believe they are larger than life in their quests to do exactly as they please without any concern for the law or anyone else. Yes, they all could be played by Sid and Pete without them losing a beat, even the numerous female ones--