Inside a museum, a tour guide greets the Sunnydale students and begins to show them the Incan burial chamber while telling a story about how the Incans sacrificed young virgins to the gods. A bit later, the Incan exhibit is deserted except for nerdy Rodney, one of Willow's classmates. He looks into the mummy's coffin and sees a sealed plate. He yanks the plate from the mummy's hand, breaking the priceless artifact. As he reaches inside the coffin to pick up the pieces, the mummy's arms grab him by the neck and draws him in.
Meanwhile, the students of Sunnydale High are excited about the new exchange program and the visiting students. Cordelia is particularly stoked to be hosting handsome Sven, a Nordic-looking hottie. Her enthusiasm wanes a bit though when the language barrier becomes a nuisance, and Cordy finds herself demoted from date to babysitter.
At Sunnydale High, Willow tells the group that Rodney is missing. They head back to the Inca exhibit to see if they can find the missing student or a clue to his whereabouts. Giles and Buffy notice the broken seal, lying next to the mummy. As Giles holds the seal, a strange man comes out of nowhere and swings at Xander with a knife. The man casts a surprised look at the open coffin and runs off.
Shaken, Willow takes a look at the mummy and notices it is inexplicably wearing braces. Either the ancient Incans knew more about modern technology than believed or something is very wrong. And since this is Sunnydale...
Meanwhile at the bus station, the exchange student Ampata is alone, waiting to be picked up by Buffy. A whispered voice calls his name. He walks in the direction of the voice. The mummy grabs his neck, pulling him in and kissing him. Ampata begins to shrivel up as the mummy literally sucks the life from his mouth. Later Buffy, Willow, and Xander arrive at the bus station to find Ampata. Buffy calls out for Ampata and a beautiful young woman appears. Xander is mesmerized by her lovely face.
The following morning, Buffy takes Ampata to school. She is visibly nervous about being around so many people. Buffy takes her to meet Giles, who comes right out and asks if she can translate the Incan seal. Ampata looks at it with shock. She is able to translate some of the images, telling Giles that it is about a bodyguard who will protect the mummy at all costs.
Xander and Ampata sit on the football field bleachers as he instructs her on the fine cuisine of Twinkies. The chemistry between them crackles as loudly as Twinkie wrappers, as the new girl laughs at Xander's zany witticisms.
Suddenly, the bodyguard attacks Xander. The guard looks at Ampata and recognizes her. Xander kicks him and takes Ampata to the library where they relay the story to Giles. Ampata tells Giles to destroy the seal, insisting that it is the root of the problem.
Ampata goes inside the girl's restroom to touch up her make-up. She sees the bodyguard standing behind her. She pleads with him to spare her: she was an innocent victim and she is in love. He is unmoved. A desperate Ampata grabs the guard in an embrace, turning him into a mummy and stealing his life force through a kiss. Her skin seems to glow even more brightly after feeding off the guard's life force.
In Buffy's room, Ampata enters wearing an Inca Princess costume for the dance. As Ampata puts on make-up, Buffy notices the girl is about to open her secret Slayer drawer. She rushes over but it's too late... Ampata has seen the weapons. An awkward moment passes. Buffy offers to unpack Ampata's trunk, lifting the lid. The doorbell rings, distracting Buffy from seeing the mummified corpse in the trunk. She rushes downstairs to get Xander as Ampata puts a heavy lock on the trunk. Xander is dressed as Clint Eastwood. Ampata comes downstairs to greet Xander. She looks stunning in her princess costume and it is clear by the expression on Xander's face that he thinks so too.
At The Bronze, the dance is in full swing as local band 'Dingoes Ate My Baby' headlines. It's fronted by Devon, a date of Cordelia's, and Oz, a redheaded guitarist. Willow is there too, dressed as an Eskimo.
Giles is at Buffy's house, letting her know that the bodyguard was found mummified in the girl's bathroom. Buffy remembers Ampata's "wigginess" and runs to her room to look through her trunk. It takes her about a millisecond to break the lock that Ampata secured it with. Slayer and Watcher are horrified to discover the corpse.
On stage, Oz stares out at the crowd and sees Willow dressed as an Eskimo and is enchanted by her quirky, endearing appearance. "Who is that girl?" he wonders. Ampata notices her hand starting to shrivel and rushes off, leaving a confused Xander alone on the dance floor. Ampata goes to the staircase and finds quiet, nerdy Jonathan sitting alone. She leads him backstage, into the darkness, as her skin reverts back to mummy form. As she moves in to give him a life draining kiss, Xander calls out for her, scaring Jonathan away. Xander asks her why she ran away. She sheds some tears and her face is clouded with pain. They finally kiss. His eyes widen with shock as he feels his life being drained. She suddenly breaks it off, and Xander falls to the floor, weakened but unharmed. She can't kill him, she realizes, because she loves him.
In the museum, Giles reads a book as he assembles the broken seal, as a way to put Ampata's essence back into her mummified body. At the party, Ampata senses something is wrong. She knows someone is reassembling the deadly seal. Buffy enters, telling Willow of Ampata's true nature. They head backstage to find Xander before something bad happens to him. Too late, they find him leaning against the wall. Xander tells the girls that Ampata has gone. Buffy realizes that the mummy must be going after Giles.
At the museum, Ampata sneaks up on Giles as he tries to put the last piece of the seal together. She takes the seal and smashes it as she grabs him by the neck. Buffy arrives and the two former friends fight. Ampata begins to leave but as Willow enters, she grabs Willow and tries desperately to kiss her. Xander begs Ampata to take his life instead of Willow's. But it's too late... for Ampata that is. She turns back to a mummy and piece by piece she falls to the floor, dead at sixteen for the second time.