Episode 17 of "Angel"
s01e17 Eternity

Wesley and Angel endure a painful experience: attending Cordelia's first stage appearance. As they stretch the truth to spare potential hurt feelings, Cordelia spots Oliver Simon, a top talent agent, and one of his clients, Rebecca Lowell, a former soap opera star, leaving a paparazzi-filled event. While Cordelia lists the many accomplishments of Rebecca Lowell, Angel notices Rebecca is in apparent danger and rescues her from an ongoing car. The next day, Rebecca pays a visit to AI and tells Angel she is being stalked by a celebrity fan. She asks Angel for his help, but he turns down the case. Wesley deduces Angel has feelings for Rebecca and has rejected the case to prevent himself from obtaining the true happiness that would unlease his evil vampire within. Cordelia is beside herself with disappointment, after all, this Rebecca woman could be a serious networking opportunity! Later that evening, Rebecca has a gathering. As she ascends the stairs she hears noises. Angel bursts in and chases out the stalker. When Rebecca glances into the mirror, she notices Angel does not have a reflection. She asks him about this, and he tells her the truth. The next day, Rebecca asks Angel to attend a premiere with her. After they make their grand entrance, they enter a secret alleyway and encounter Rebecca's stalker. Angel manages to drag him down. When Rebecca realizes the stalker is a stuntman and former client of Oliver's, she confronts him. When Oliver mentions no one stays young forever, Rebecca glances at Angel and gets an idea. The next day, she and Cordelia go shopping and Rebecca pumps her for information. That night, she comes over in a sexy number and gives Angel a bottle of champagne to thank him for his valiant efforts. She slips a drug into his drink and moments later, tells him she wants to become a vampire. The drugs begin to affect Angel's judgment, and moments later, the persona of Angelus emerges. After an exchange of evil pleasantries, Cordelia and Wesley manage to knock him out and keep him contained until the drugs wear off. The next day Angel apologizes to Cordelia and Wesley for his behavior.