On a routine night of patrolling, Buffy encounters a pair of mouthless demons. While she kills one of them on a table at the park, the other demon manages to flee the scene. As she leaves, Buffy fails to notice the dead demon's blood on her hand, which quickly absorbs into her skin.

The next morning, after learning from Willow that everybody will be attending the basketball game later that night, Buffy decides to check out the itch on her hand that's been bugging her all day. In the library, Giles finds an article on the demon that Buffy killed. In it, he learns that physical contact with the demons can cause an infection, in the form of an assimilation of one of the demon's traits. Later that night during the game, Buffy patrols the streets of Sunnydale by herself. She bumps into Angel, whom she has been distant from ever since the trick they played on Faith.

While talking to her friends the next day in the lounge, Buffy inadvertently hears Xander's own thoughts. On the way to the library, she realizes that she can hear what each student is thinking. At the library, Giles concludes that the demons must have communicated telepathically if they had no mouths. Buffy uses her newfound trait to impress her teacher in English class. During the class, Buffy hears some grim thoughts coming from Freddy Iverson, one of the writers for the school newspaper. After class, Buffy visits Angel at the mansion and tries to learn what's going on inside his head. However, Angel informs Buffy that her power can't work on a vampire's mind. He then tries to assure Buffy that he was never tempted by Faith during the entire ordeal that revealed her affiliation with the Mayor.

Buffy returns to the library, where her friends have just learned of the Slayer's new ability. Disturbed and intimidated by this sudden intrusion into their privacy, Xander, Willow, and the others find it tough to be around Buffy. In the hallways, Buffy starts to realize the true downside to her mind-reading ability, for the abundance of thoughts coming from all directions proves to be overwhelming. In the cafeteria, a mental declaration to murder all of the students the next day is heard by Buffy. She tries to identify the source of the thought, but the overflow of thoughts causes her to pass out.

Outside, Buffy regains consciousness and tells the others about the murder plan she discovered. While Buffy goes home to rest, the gang tries to locate the suspect. They try to interrogate all of the prime suspects, but Oz has trouble tracking down Freddy. Meanwhile, Giles and Wesley learn that Buffy needs to consume the heart of the second demon in order to be cured of her mind-reading power. With the Slayer out of action, Giles turns to Angel for help. After hunting down the demon over the course of the night, Angel finally succeeds in obtaining its heart. He brings it to the Summers' home and feeds it to Buffy. Eventually, Buffy wakes up and discovers that she can no longer read anybody's mind.

Back at the school, Xander, Willow, Cordelia, and Oz corner Freddy in the newspaper office. Upon learning that he has nothing to do with the murder plot, Cordelia finds an announcement on the desk from Jonathan that apparently admits to the planned killing. Buffy arrives at the newspaper office just in time to help the gang search for Jonathan. While Xander gets distracted by some tasty treats in the cafeteria, Buffy runs out into the courtyard, where she spots Jonathan assembling a rifle at the top of the clock tower. Running out of time, Buffy takes the shortest route possible to the roof. Just as Jonathan attaches the final piece, Buffy crashes into the room. Aiming at rifle at Buffy, Jonathan tries to prevent her from getting in the way of his plan. He tells her how fed up he is with how everybody treats and thinks of him. Buffy responds by telling Jonathan that everybody has their own pain, regardless of how good their lives may seem on the outside. When Jonathan finally hands over the rifle, he shocks Buffy by telling her that he intended to kill himself, not the other students.

Inside the cafeteria, Xander witnesses the lunch lady pouring rat poison into a large pot in the kitchen. He runs out and warns everybody about the lethal lunch special. Xander trips and falls to the floor, giving the lunch lady enough time to tower over him with a large butcher knife in her hand. Luckily, Buffy arrives on the scene and puts the lunch lady down for the count.

Willow learns from Buffy that things are going better with Angel, now that some uncertainties about his feelings for Buffy are no longer an issue. After meeting up with Giles, Buffy shocks him by revealing her awareness of his escapades with Joyce while under the influence of the mind-altering candy.

Episode synopsis by Alan Hufana