Loved this episode. The script is sharp & it's actually plotted better than a lot of Film Noir films, not least in that you're highly unlikely to guess the denouement.
One tiny negative: I was waiting for Quagmire to show up in a part, but for some reason they didn't give him a role in this outing. No matter
Trigger warning: the episode deals with some weighty social issues like the inter-war racism and the inequality of horses being allowed to crap in the street while humans could not. Fortunately most American cities seem to have redressed that grave injustice.