The Hard Way (movie, 1979)

John Connor is a soon-to-retire hitman that agrees to take on one last job. After years plying his deadly trade, he has finally had enough. Seeking to retire to Dublin and maybe salvage his dying marriage, Connor wants to leave the lonely world of the marksman behind him and melt into the background. Unfortunately, his handler O'Neal is reluctant to let him go, and, after much coertion, manages to talk him into accepting one final job.