Buffy The Vampire Slayer Star World, 8pm Fuelled by powerful black magic, vengeful Willow (Alyson Hannigan) targets Andrew (Tom Lenk) and Jonathon (Danny Strong) for destruction, leading to a spectacular battle with Buffy (Sarah Michelle Gellar). In Africa, Spike (James Marsters) faces off against a seemingly unstoppable foe in order to become what he once was. Also starring (above from left) Michelle Trachtenberg, Marsters, Gellar, Amber Benson, Hannigan, Anthony Stewart Head, Nicholas Brendon and Emma Caulfield. The Autism Puzzle Pearl, 9.30pm In the 1960s, autism was considered a rare disorder that affected just four to five children in every 10,000. Now, however, some experts are claiming that the figure is as high as one in 86. This documentary looks at the history of the condition and current research into causes, treatment and prevalence.