The picture will follow "a New Orleans police detective (Cena) whose girlfriend is kidnapped." Harris will play an FBI agent, presumably helping on the search, White is a cop who works with Cena's character, and Gillen, who used to be sweet as Aidan in Circle of Friends, is taking on the role of the kidnapper. According to IMDb, that also makes him an "evil crime lord" who forces him to go "12 Rounds," hence the film's title.
Should this work out as well as Cena's last WWE feature, The Marine, this should be a sweet moneymaker for the company. In the meantime, we've got to see if any of the rumored cast sticks around -- everyone from Al Pacino to Piper Perabo and Method Man have been rumored to have parts.