Ben Affleck turns director to helm this gripping adaptation of a mystery novel by Dennis Lehane (the guy who also provided Sean Penn with Mystic River). Casey Affleck delivers an understated star turn as a youthful, but charismatic Boston P.I. who--along with his attractive g.f. Michelle Monaghan (The Heartbreak Kid)--is hired to help out in a child abduction case. A little snooping through Beantown's seedier neighborhoods roots out a mother with some very ugly underworld connections and a growing conspiracy. Some of the plot mechanics might not be entirely realistic, but Affleck has created a gritty and quite realistic portrait of low-rent Boston. 114 minutes R.