Frank Langella provides the main reason to see the sometimes sentimental Robot & Frank -- a movie about an aging man whose son buys him a robot, a machine that's meant to help Langella's character cope with an increasingly debilitating case of dementia. Langella's Frank spent most of his adult life as a jewel thief, and only recently has gotten out of the slammer. Fearing that Frank will do harm to himself, his son (James Marsden) arranges for Frank to have a robot that cooks and cleans for him, as well as generally organizes his life. It doesn't take too much foresight to know that the robot (voiced by Peter Sarsgaard) is going to develop an odd-couple relationship with Frank, who's as haphazard in his ways as the robot is fastidious. The twist: Initially reluctant to accept assistance, the crusty Frank begins to change his mind when he realizes that the robot can help him plan a heist. The robot reluctantly goes along with the scheme, thinking Frank will benefit from an activity that really involves him. The movie takes place in the near future, but director Jake Schreier doesn't overdo the futuristic touches. The town librarian (Susan Sarandon in a lovely small performance) is being asked to get rid of books and go electronic, but mostly the movie looks very much like the present. Liv Tyler makes a drop-in appearance as Frank's daughter, a young woman who, on principle, opposes robot help. Amid all of this, the movie manages to deal with aging and a loss of memory that's more frightening to us than to Frank, who seldom acknowledges the severity of his deficits. No need making too much of Frank & Robot, but the movie deserves credit for coming close to turning a comic fantasy into a sensitively realized look at the sadness of aging.