When four year old Madeline disappears from one of the toughest neighbourhoods in Boston, her aunt, Beatrice McCready hires two private detectives, Patrick Kenzie (Casey Affleck) & Angie Gennaro (Michelle Monaghan), to find her. Initially not wanting to take on the case, the two find themselves having to face drug dealers, criminals and paedophiles, as well as a moral predicament that tears them apart.