Can a youthful mistake be amended in one’s old age? What if the memory of it is unreliable? These are the central questions behind the British art house entry, “The Sense of an Ending.” Oscar-winner Jim Broadbent plays a man whose former girlfriend’s mother leaves him a mysterious diary in her will. Problem is, the old girlfriend refuses to give it to him. While the movie never quite mines the depth it seeks, it’s an interesting effort that’s impeccably acted.