It's the Roaring `20s and Prohibition hasn't stopped the flow of booze in an underground network of gangster-run speakeasies. The opportunity to gain power and money is there for any man with enough ambition and nerve, and Joe Coughlin, the son of the Boston Police superintendent, long ago turned his back on his strict upbringing for the spoils of being an outlaw. But even among criminals there are rules, and Joe breaks a big one: crossing a powerful mob boss by stealing his money and his moll.