When the Italian Mafia threatens to kill a crooked bookie (John Turturro), Irish mob boss Leo O'Bannon (Albert Finney) refuses to allow it, chiefly because he's dating the bookie's sister, crafty gun moll Verna Bernbaum (Marcia Gay Harden). Leo's right-hand man, Tom Reagan (Gabriel Byrne), is also seeing Verna on the sly, and when he's found out is obliged to switch sides, going to work for the Italian mob amidst a dramatically escalating gang war over liquor distribution.