The use of N.W.A.'s hardcore hip-hop anthem Straight Outta Compton early in Venus and Serena underlines the unlikelihood of two black sisters emerging from the notorious California suburb to dominate the sleek, chic world of professional tennis. For the most part, though, Maiken Baird and Michelle Major's glossy documentary elides cultural analysis and does its best to keep up with the fluctuating fortunes of its subjects, who had their share of problems on and off the court while the cameras were rolling in 2011. Both Serena and Venus show admirable candour in the interview segments, but that's unsurprising considering how long and hard they've been grooming themselves for stardom. The most affecting passages concern Venus's cabin fever when an autoimmune disease forces her under house arrest, but the reality-TV presentation keeps even the unruliest emotions safely packaged for audience consumption. In tennis terminology, Venus and Serena is a soft lob.