Buffy is on patrol, even though she's suffering from the flu that's taken half the student body of Sunnydale High out of school. She nearly stakes Xander, who, along with Willow and Cordelia, are on patrol for Buffy because she's sick. She argues with them that
she's the Slayer, and only she can stop Angel. Right on cue, Angel shows up and attacks. Buffy fights him, but weakly, and Angel has her at his mercy until the others drive him off with crosses. Buffy then collapses.
They take her to the hospital, where Dr. Wilkinson tells them and her mother that she'll be fine but that she needs to stay a few days. That doesn't sit well with Buffy, who really wants to go home. Delirious, she rages, yelling about vampires, until the doctors sedate her. Joyce explains that Buffy hates hospitals, and has ever since she saw her beloved cousin Celia die in one when she was eight. She thanks Giles for looking out for Buffy, and expresses her sympathy for the death of Ms. Calendar. 
Meanwhile, Willow and Xander worry that Angel can get into the hospital any time he wants. That night, Buffy wakes up delirious with fever, and sees a young boy at her door. The boy leaves, and as Buffy watches, the boy is followed by a grotesque humanoid figure dressed in black. She gets up and tries to follow, but after having hospital memories of when she was eight, she wakes up again in her bed. Getting up again, she goes to the children's ward, where she sees a dead girl being wheeled away, and she hears Dr. Wilkinson argue with a doctor named Backer about his controversial methods. The young boy she saw, Ryan, comes up behind her and tells her, "He comes at night. The grown-ups don't see him. He was with Tina. He'll come back for us." When Buffy asks who he's talking about, Ryan replies, "Death."
As Xander waits outside Buffy's hallway, Angel arrives with flowers. Xander stands up to the vampire and his threats, and Angel leaves, but not before taunting Xander. "You still love her," Angel laughs. Dr. Wilkinson tells Buffy the fever's gone down and is amazed by how fast she's healed. Then Giles and her friends arrive, and she tells them about the previous night. Cordelia tactlessly accuses Buffy of feeling bad about her cousin's death, and of making up a monster to fight so she doesn't feel so helpless. Buffy disagrees, saying that Ryan is afraid of something real. That night, Xander and Cordelia go through the hospital's files to see what killed Tina. They're almost caught by a weasely security guard, but Cordelia flirts with him, allowing Xander to escape with Tina's file. Xander confronts Cordy about her flirting, and she counters with his obsession with protecting Buffy. Buffy visits the children's ward, where Ryan is drawing a picture of the creature he calls Death. Buffy tries to reassure him, but he says, "Can't fight Death." Willow and Giles have surmised that the children are afraid of a real person and think it could be Dr. Backer, who they find has a spotty record of unauthorized experimentation and mysteriously dropped malpractice suits. Meanwhile, Dr. Backer seems to have a breakthrough, and goes to the children's ward to test it. There, though, he is attacked by an invisible creature that slices him open, while Buffy watches from the door. When she tries to help, the creature hits her and drags Dr. Backer's body away.
Buffy gives Ryan's picture to Giles, and when her mother arrives to take her home, Buffy demands to stay, claiming a resurgence of her symptoms. The gang sets to work. Sneaking into Dr. Backer's office, Willow and Buffy discover that his work had been legitimate, and had been genuinely helping the children. And at the library, Cordelia and Giles discover the creature's identity. It's called the Kindestod, and it kills children by sitting atop them and then sucking the pinned child's life out. The description triggers a memory in Buffy, and she realizes that her cousin Celia was killed by the Kindestod. She realizes that the fever she had allowed her to see it, so Willow deliberately re-infects her with one of Dr. Backer's samples. They return to the children's ward, but it's empty.
The kids are heading to the basement, and as Buffy watches, the Kindestod appears in the empty ward and follows them. Willow helps her elude the hospital's security guards, and she meets up with Xander, who helps her down to the basement. There the Kindestod has cornered the children, and she attacks it just as it's about to feed on Ryan. The fever impairs her fighting, though, and as Xander leads the children to safety, the Kindestod pins Buffy. His eyes extrude towards her, ready to drain her life... and she reaches up and snaps his neck. Buffy finishes recovering from the fever at home, where she receives a curiously gruesome drawing from a grateful Ryan.
