The first season begins several months after the events of the movie, with Buffy Summers arriving in Sunnydale with her mother, Joyce.
After moving with the hopes of leaving her born slayer duties behind, Buffy inevitably comes into contact with her Watcher, the librarian Rupert Giles, and the two friends who would fight demons alongside her through the series. They soon realize that Sunnydale High is located on a Hellmouth, a portal to demon dimensions, which attracts supernatural phenomena to the area.
The first season included mostly standalone episodes, exploring the problems faced by the student population as a result of the centrality of the Hellmouth that it has. Such issues explored include: ignored students turning invisible; witches; demon teachers; and the never-ending supply of vampires.
With the high emphasis on teenage angst and metaphorical nature of the episodes, Buffy's inevitable love interest came in the form of Angel, who frequently turns up with cryptic warnings for Buffy. However, the relationship becomes complicated when the truth about Angel's past is uncovered. Angel is a vampire with a soul that was restored by gypsies many years prior to the series beginning.
The overarching plot concerned The Master's attempts to reach the surface. He is an ancient and very powerful vampire who was trapped by an earthquake caused by his attempt to open the Hellmouth decades ago. Buffy and her comrades manage to stop each supernatural threat, typically employing a combination of detective work, frequent physical combat, and extensive research of both ancient mystical texts and computer-accessible records.
Ultimately, The Master recruits a prophesied Anointed One who brought Buffy to her death in The Master's underground prison. He used her blood to escape to the roof of Sunnydale High, but she is quickly revived by Xander, who had tracked her with the help of an unfed Angel. She manages to throw the Master onto a shard of wood, and the Hellmouth is closed.
Buffy Summers arrives in Sunnydale and is not happy to meet her new Watcher, Rupert Giles. A mysterious "friend" offers guidance, but Buffy resists her destiny until Willow Rosenburg and Jesse McNally are abducted. Buffy saves Willow from an ordinary vampire, but loses track of Jesse in a confrontation with Luke, the Master's vampire vessel.
After escaping from Luke, Buffy goes in search of Jesse, with a little help from Giles and Willow, from her mystery friend, Angel, and from Xander, who braves the dank, dark sewers with her. The Master plots the Harvest, a ritual designed to imbue him with strength enough to open the Hellmouth, but Buffy defeats his minions in a showdown at The Bronze.
Buffy tries out for Sunnydale's cheerleading squad. The Scoobies at first suspect that Amy Madison is causing all the havoc but discover that her mother, also a practicing witch, has swapped bodies with her.
Xander is smitten by the substitute biology teacher, Ms. French, who turns out to be a giant praying mantis terrifying enough to make vampires run for cover. Angel's warning gives Buffy a vital clue and she rescues the virgin male students—including Xander—chosen to fertilize the creature's eggs.
Buffy's lovelife is looking up when she goes on a date with the normal Owen Thurman, but when Owen nearly gets killed during Buffy's battle to save Giles and the others from The Master's vampires, she decides that "normal" dating might be too dangerous after all.
At the zoo, Xander and four other students sneak into the off-limits hyena habitat and become infected by an evil demon spirit. Xander and his pack grow more and more feral until Buffy, Giles and Willow reverse the spell.
Sharing their first kiss, Buffy is horrified to discover that Angel is a vampire. Bent on slaying him, Buffy learns that Angel's soul was restored by a Gypsy curse, making him unique—and reviled—among his fellow undead. Angel stakes Darla, the vampire who made him, as she attempts to assassinate Buffy for The Master.
Willow meets a boy on the Internet, but "Malcolm" is really Moloch the Corrupter, an ancient demon released from bondage after Willow scanned his "book" into the school's computer. With help from Jenny Calendar, Sunnydale High's computer teacher, Buffy foils Moloch's plan to upload himself into a giant robot.
After Principal Flutie's death, the new sheriff in Sunnydale High, Principal Snyder, forces Buffy and her friends to participate in the school talent show. When a girl's heart is harvested, Buffy suspects a fellow student and his strangely talkative dummy.
Ignored by students and teachers alike, Marcie Ross literally becomes invisible, then uses her affliction to terrorize Cordelia and her friends. Sympathetic at first, Buffy nevertheless stops Marcie when she goes too far. Men in black come to take Marcie away.
Buffy quits Slaying when a prophecy predicts she will die in battle against the Master and The Anointed One, but soon puts aside her fear and enters the fray on her own timetable and terms. In fulfillment of prophecy, The Master indeed kills the Slayer and opens the Hellmouth, but learns too late that Buffy is resilient, unpredictable—and lethal.