A feature-length defense of dirty old man syndrome, Venus charts the occasionally sweet but often icky relationship between an aged British actor named Maurice (Peter O’Toole) and the rebellious teen niece (Jodie Whittaker) of his friend. It’s a relief that the movie isn’t mawkish, but it goes too far once sexual favors become involved. What gets lost amid the sensationalism is a harsh but honest look at aging and a shockingly vulnerable performance by the screen legend of Lawrence of Arabia. O’Toole is still gallant enough to almost, almost redeem the lecherousness.