Prime (12A) <!-- none onestar twostar threestar fourstar fivestar -->

You may remember a few years ago the arrival of "middle youth", the women for whom 40 is the new 30, and getting older doesn't mean you stop having fun. Prime is aimed squarely at them. Uma Thurman plays a 37-year-old divorcée who falls for a handsome 23-year-old student (Bryan Greenberg). As if the generation gap wasn't enough - while her biological clock is ticking, he wants to pass the time playing with his Nintendo - there's a twist: his mother turns out to be her analyst; and while the analyst is encouraging her patient to forget about guilt, enjoy life, who cares if he's young, the mother is telling her son to drop this and settle down with a nice Jewish girl. How Meryl Streep got embroiled in that part, heaven only knows. The first half runs along smoothly enough, but when things turn more serious it gets over-sentimental and crashingly dull - I was alarmed, examining my notes, to discover I'd been covering the page with doodles.