A strange man meets Dr. Oliver Mitchell in a parking garage. The man, Gavin, speaks fulsomely about Dr. Mitchell's work – and then opens a third eye on his forehead. A ray comes from the third eye and burns through Dr. Mitchell's skull, killing him.
The sisters are getting ready to see a movie when Piper's boss at Quake, Martin, calls her in–on her day off. A convention is in town and Quake is short-staffed. Prue and Phoebe are worried; Piper's been working a crazy schedule of late. She was supposed to talk to Martin about it weeks ago, but never got around to it. Phoebe happens to bump into Gavin and gets a premonition of a woman being killed. The police arrive and the sisters find Dr. Mitchell's dead body. Phoebe thinks her vision was of the next murder. Piper and Phoebe continue to argue over Leo. Prue thinks Phoebe only likes Leo because Piper does. Prue is unwilling to talk to Andy, feeling it's too soon after they broke up. Phoebe goes in her place to ask about Dr. Mitchell's murder. Prue looks through the Book of Shadows, but can't find anything. As she leaves, the Book flips on its own to a truth spell. Prue is skeptical and closes it back, only to for it to reopen to the spell after she left.
Phoebe has talked to Darryl about the case. She passed Andy in the parking lot and tells Prue that he still cares about her. Phoebe also suggests that Prue tell Andy that she's a witch, if only to see how he handles it. Martin overworks Piper, and she doesn't complain.
Prue casts the truth spell, not knowing that Phoebe and Piper are in the house and will also be affected. She calls Andy, but only reaches his answering machine. Piper asks if Phoebe can see a pimple on her chin. Phoebe is initially reluctant to answer, but just then the spell takes effect and to her shock says she can see it after all. Piper admits she didn't tell off Martin.
Phoebe and Piper notice that they are unable to lie. Phoebe admits that she only likes Leo because Piper does. Prue admits to casting the truth spell, to determine if Andy is okay with her being a witch. For the next 24 hours, anyone who comes in contact with them will have no choice but to tell the truth. Gavin walks into a laboratory and finds Alex Pearson working there. He kills Alex with the third eye, but not before Alex rips a button off of Gavin's coat.
Phoebe goes to Andy and asks him about the murders. Andy tells what he knows. Both of the victims had the same burn mark on their forehead, and it looked like all the life had been sucked out of them. He mentions the button, and says it's made of a strange alloy never seen before. She leaves, and Andy calls Prue. He offers to meet after interviewing a witness.
Piper is called into Quake yet again. Leo comes in, asking to use the washing machine. Piper asks if Leo thinks of her; he does, and thinks Piper has beautiful eyes. She asks, "What do you think about women who make the first move?" Leo says, "I’m still waiting for it to happen." and Piper kisses him. Just as Prue gets off the phone with Andy, Tanya Parker, the sandwich girl, stops by her office. Hannah follows, and snatches a sandwich Tanya was saving for Prue. Under the influence of the spell, Hannah admits that her mission in life is to destroy Prue. Rex pulls her aside and warns her to keep quiet. Hannah lights Rex's cigar, apparently with a magical power, by blowing on it.
Rex stops by the elevator to check on Prue. Under the influence of the spell, Prue nearly blurts out that she's a witch, but Phoebe cuts her off. Just as Phoebe despairs of finding the woman in her premonition, she sees Tanya walking by and recognizes her as the woman.
Piper is overworked. Martin, under the spell, admits to overworking her to keep from spending money on more employees. Piper angrily quits. Phoebe rushes down to stop Gavin while Prue calls security. Phoebe finds Gavin and Tanya struggling, with Gavin getting the better of it. Just as Gavin starts to blast Tanya, Phoebe smashes a bottle over his head. They drive off to the manor. Phoebe explains that the man who attacked her was a demon. Tanya tries to run, but Phoebe convinces her to stay.
Andy goes to Prue at Buckland. Prue demonstrates her power and explains that she is a witch. Andy becomes uncomfortable. She asks him whether or not he can accept that part of her, and he admits that he doesn't know.
Gavin comes into Prue's office. Under the influence of the truth spell, Gavin admits that he is from the future. He was sent to kill Tanya to keep her baby from being born, since he will someday create a vaccine.A biogenetics professor at Stanford has been killed. Three of the victims work in the biotech field, Piper and Phoebe don't see how they're connected to Tanya, a sandwich girl. Phoebe touches Tanya and gets a premonition of Tanya holding a newborn baby. Phoebe realizes that Tanya is pregnant, and also remembers the button the police found wasn't made of anything the cops had seen before. Phoebe suspects Gavin is from the future--and isn't after Tanya, but her baby.
Piper can't reach Prue at work, and heads to Buckland's to check on her. Prue flees into a warehouse and hides from Gavin. Piper finds Prue's office empty. Prue asks Gavin what the vaccine is for and he admits that the vaccine will destroy warlocks like him. His other victims will help with the research that creates the vaccine. Gavin realizes something's up and charges at Prue, but she pins him against the wall with her desk and escapes. Gavin finds Prue and grabs her by the neck. He's about to blast her when Piper rushes in and freezes him, freeing Prue. Gavin unfreezes and the two shove a crowbar into his third eye, killing him.
Prue goes to Andy and asks how he feels about her being a witch. He is still uncomfortable. The truth spell expires in that moment and Andy doesn't remember what they were talking about, nor that Prue is a witch.
Martin, likewise, doesn't remember that Piper quit her job and orders her into the kitchen while she is having dinner with Prue. She demands that Martin hire some more people or she will quit. He agrees, to Piper's surprise, and she walks out of the kitchen. As she leaves, she smacks the door into Leo, who apparently does not remember the kiss. Piper offers to buy Leo a drink. Prue enters Quake and tells Phoebe about the rejection from Andy. Phoebe hugs Prue to comfort her.