Piper dreads going to her ten year high school reunion, to be held at P3. She wasn't very popular in her high school days, and feels she really can't go as herself even though she's the owner of a very successful club. Prue and Leo try to encourage her. Prue offers to give Piper a makeover. Leo suggests Prue and Piper bring Phoebe with them to cheer her up; she's been somewhat distant since Cole's disappearance. Prue thinks Phoebe needs some time after finding out her boyfriend was a demon.
Kierkan, a powerful alchemist, argues with Terra, a female life essence he created. Terra wants to be free. Just as Kierkan is about to alter Terra's chemistry, she stabs herself, and her spirit escapes. Later, it rises from a grating and enters a businessman. The businessman's soul, now a reflection in a window, cries for help, but Terra tells him it won't do any good. She orders him to find the Charmed Ones.
Piper is still nervous about going to the reunion, but Prue tries to buck her up. Prue thinks the reunion can't go any worse than her last date. She's started making lists again to weed out dates, and her last one scored a two due to unusually bad breath. Piper offers to scout out guys at the reunion, but Prue isn't interested. Phoebe walks in, and Prue and Piper invite her to come along. However, Phoebe says she has some studying to do at the library.
Piper, Prue and Leo are taking some stuff to the car for the reunion, Justin Harper, a classmate of Piper who had a big crush on Prue, stops by. He initially mistakes Prue for Phoebe. Leo gets a jingle from the Elders, which makes Piper unhappy. Leo reassures her that she'll have the cutest date and orbs away.
Terra is watching from the businessman's car, looking to get one of the sisters alone. The man's soul begs her to let him go, but Terra tells him leaving his body will be a bit "messy." It won't matter in any event; the man's soul is getting weaker and will eventually die.
Phoebe is at the mausoleum where she had pretended to vanquish Cole, and tells herself she has to tell the truth. She has a vision of Cole's father being killed by a female demon, and finds that Cole's father is buried here. She is taken aback by the date Cole's father died, 1888.
Piper arrives at P3 and finds Missy Campbell, the homecoming queen during her senior year. Missy insults and belittles Piper by making her take out the trash in her own club. Prue, who wants to defend Piper is stopped by Justin, who says Piper has to find her own legs. He remembers how Piper got so nervous during her run for freshman class secretary that Prue had to finish her speech for her. He admits he deliberately mistook Prue for Phoebe because he isn't interested in Prue anymore; she made him drool through most of high school. Prue discovers Justin is making lists for his dates as well. Terra walks downs the stairs of P3.
Prue sees Piper hauling a trash bag out and tries to buck her up, but Piper says that being around her old high school compatriots makes her feel like her 16 year old self. She does, however, intend to get rid of the balloons and streamers. Terra follows Piper out to the dumpsters. He stabs himself and Terra emerges and enters Piper. Terra sees Piper's soul in her reflection. In the office, Piper threatens to vanquish Terra if she doesn't get out of her body, but Terra ignores her and goes back to the party.
Missy continues to bark orders at Piper/Terra. Prue encourages Piper/Terra to stand up for herself, and Piper/Terra finally curses Missy out, telling her to move the trays herself. Suddenly, Piper summons up enough strength to beg Prue for help. Before Piper can explain, Terra takes over again, and talks Prue into letting her go home to rest.
Kierkan finds the body of the businessman and revives him with a spell. He asks the businessman where Terra went. The businessman says Terra went to the manor. Keirkan then kills the businessman again.
Phoebe goes to the Historical Society and learns that Benjamin Coleridge Turner had died in 1888. He had a wife named Elizabeth, but there is no record of her death or Cole's.
Terra demands that Piper tell her what her powers are; she suspects Kierkan is after her. Piper is only willing to help Terra if she leaves her body. Piper warns Terra that Prue and Phoebe will figure out what's happening and if she dies, they'll hunt Terra down. Terra tells her than in a few hours she will die anyway, then decides to trick Prue and/or Phoebe into helping her vanquish Kierkan.
Prue deliberately makes things difficult for Missy; when Missy wants Prue's help with the DJ, Prue twitches her finger and drops all the balloons onto the floor. Justin notices this has happened two times before; he thinks that P3 is haunted by a poltergeist. Prue is surprised that Justin believes in the supernatural. Just then, the phone rings; it's Piper/Terra who reports finding a demon in the house. Prue asks if she froze him. Piper/Terra is intrigued that Piper has that power. Piper warns Terra that her sisters will figure out something's amiss, but Terra threatens to kill Piper and possess either Prue or Phoebe, and kill them if they don't cooperate. Piper reluctantly tells Terra where to find the Book of Shadows.
Prue picks up Phoebe from the Historical Society. While they're on their way back to the manor, Terra is keen to vanquish Kierkan. Piper tries to tell Terra that it takes the Power of Three to vanquish an alchemist. Just then, Keirkan barges into the manor and knocks Piper/Terra down. Just as Kierkan is about to stab Piper/Terra, she freezes him, telling him that he just pissed off a Charmed One. Prue and Phoebe enter after him and the three read a spell, and Kierkan says he could have helped them before he dies. Keirkan drops a small bottle as he goes up in flames.
Prue and Phoebe want to find out more about the female demon who's after them, but Piper/Terra doesn't think they should take a demon seriously. Piper/Terra is about to walk out to change when a weakened Piper tries to warn Prue and Phoebe that Terra is killing her. Before Prue can find out more, Terra takes over again, and walks out. Prue wonders why Phoebe didn't tell her she was really at the Historical Society, and Phoebe admits she still has feelings for Cole, but not for Belthazor.
Piper/Terra has shucked her black suit and pearls for a hot red halter top and skin tight black leather pants. Piper offers to spare Terra if she leaves willingly, but Terra isn't willing to give up Piper's powers. Piper sees Leo orbing in, and says that if Prue and Phoebe don't kill Terra, "my boyfriend Tom" will. Terra addresses him by that name and passionately kisses him, but he notices the difference. Leo is suspicious and Terra blasts him into a wall, knocking him out.
Prue finds the page on alchemists in the Book of Shadows. Phoebe sees Piper/Terra leaving without Leo or saying goodbye to her sisters. Prue reads about life essences in the Book. Alchemists usually store them in a small bottle called an essence bearer. Prue suddenly remembers Piper's strange behavior. She believes Piper is possessed and that the bottle Kierkan dropped is an essence bearer. She and Phoebe start working on a spell.
At P3, Piper dances barefoot on top of the bar to EMF's "Unbelievable", in a scene similar to one in Coyote Ugly. Prue and Phoebe arrive, pull Piper outside and read the spell. Piper/Terra staggers, but nothing else happens because the dispossessing spell requires the Power of Three. Terra tells them that she has an alchemist's powers since she was made from Kierkan's blood and she's grown even more powerful being in Piper's body. They call for Leo, but he is still unconscious. Terra tries to blow past Prue and Phoebe and head back to the party, but Prue flings Piper/Terra into a dumpster and orders her out. Piper/Terra pulls the dagger out of the businessman's body, but Prue begs her not to kill Piper. Inside P3, the sisters try to drag Piper back to the manor. Prue and Piper/Terra get into a fight, with Missy side commenting about how she knew that Prue and Piper were not that close.
Back at the manor, Prue stays with Piper while Phoebe awakens Leo. Prue apologizes to her unconscious sister and then flings a knife into Piper's chest, puncturing her heart and releasing Terra. Phoebe and Leo rush in and Leo is distraught explaining to Prue that he can't heal the dead. Terra then possesses Leo, as was Prue's plan all along.
Prue and Phoebe offer to let Terra destroy her essence bearer if she revives Piper, otherwise, they'll stab Leo and suck Terra back into the bearer for good. Leo/Terra revives Piper. The sisters hand the bearer to Leo/Terra, who smashes it. The sisters then start the dispossessing spell. Realizing she's been double-crossed, Terra tries to blast them, but Prue deflects the blast into a mirror. The sisters finish the spell and eject Terra from Leo. Terra blows up almost immediately; since she destroyed the essence bearer, she had no means of survival. Leo finishes healing Piper, who was still bleeding.
Prue and Phoebe tell Piper about the show she put on when Terra possessed her. Piper thanks Leo that he knew the difference between her kisses and Terra's. She also sarcastically thanks Prue for having the courage to kill her. Prue and Justin agree to go on a date sometime.
Leo notices Phoebe still seems sad over Cole. She tells him that Cole seduced her and she let him. Leo tells her that nobody knew that Cole was evil. Phoebe tells him that he's still alive...in her heart.