Can you buy the notion of Jennifer Lopez as a hit woman, even in a romantic comedy? It doesn’t look like she, costar Ben Affleck, or writer-director Martin Brest can, even though that’s the setup. Lopez and Affleck play heavies assigned by a crime lord to watch over the kidnapped, mentally challenged young brother (Justin Bartha) of a federal prosecutor, but this is less a narrative than a lecture-demonstration on the innate superiority of the New Agey woman’s brains, style, femininity, and open bisexuality over the old-fashioned man’s bad taste, violence, and seemingly straight macho bluster. For the most part I was able to accept this thesis and enjoy Lopez in her usual superwoman role, but the script does get awfully preachy in spots. Brief but flamboyant cameos by Christopher Walken and Al Pacino helped keep me distracted from the noble intentions and the silliness. 124 min. (JR)