Finally, a story. So reads the screenwriter's epitaph, according to the old joke. That dilemma, the unending quest for a good story, is one that Marty (Colin Farrell), an Irishman living in Hollywood, understands all too well. His agent calls to remind him that his next screenplay is due. Unfortunately, Marty has made little progress, beyond a bold if rather literal title: Seven Psychopaths. Thus begins the film within a film, or perhaps film about a film by another Irishman, Martin McDonagh, also in Hollywood and lapsing into a major sophomore slump after his surprising debut, I n Bruges (2008). Seven Psychopaths might be only the second full-length feature for Mr. McDonagh, but for his part, he already seems to be a writer running desperately short of ideas. The subject matter in Seven Psychopaths , aside from the screenwriter's dilemma and, well, psychopaths, is hit men. Such was the subject of McDonagh's vastly more original d...