The fourth season of the television series Buffy the Vampire Slayer premiered on October 5, 1999, on The WB and concluded its 22-episode season on May 23, 2000. It maintained its previous timeslot, airing Tuesdays at 8:00 pm ET. Beginning with this season, the character of Angel was given his own series, which aired on The WB following Buffy. Various Buffy characters made appearances in Angel, including Buffy herself; Cordelia Chase, formerly a regular in Buffy, and Wesley Wyndam-Pryce, who appeared in Buffy season three. Plot Season four sees Buffy and Willow enroll at UC Sunnydale while Xander joins the workforce. The vampire Spike, having been left by Drusilla, returns to Sunnydale and is abducted by the Initiative, a top-secret military installation based beneath the UC Sunnydale campus, led by Maggie Walsh. They implant a microchip in his head which prevents him from harming humans. He reluctantly helps the Scooby Gang throughout the season and even begins to fight on their side after joyfully learning that he can harm fellow demons. Buffy and her friends still don't trust him, except Willow who opts to give him a chance to redeem himself, which he eventually does. Oz leaves town after realizing that he is too dangerous as a werewolf and after an horrific encounter with the Initiative. Willow falls in love with Tara Maclay, another witch, and the two begin a relationship. Another focus of the season is Xander's relationship with former vengeance demon Anya Jenkins, who becomes infatuated with him due to him making her feel human and Xander returns these feelings as she makes him feel like a man. Anya tries to get Xander off her mind, but feelings develop which they finally acknowledge and begin a relationship. Buffy begins dating Riley Finn, a grad student who she later discovers is a member of the Initiative. Riley tries to involve Buffy in the organization, initially it seems successful, with Initiative leader Professor Walsh impressed with Buffy's incredible fighting skills, and allowing her a security pass and pager, but Buffy's questions and non-military free spirit worry Walsh who sees it as a threat to her plans and potential bad influence on Riley, threatening his allegiance to the Initiative. After Buffy and Riley's first sexual encounter, seen by Walsh via a hidden camera, Walsh plots to kill Buffy, which fails but causes Riley to cut ties with Walsh and the Initiative.