Prue and Piper prepare the vanquishing potion needed to destroy Belthazor. It's a heavy-duty one calling for several ingredients. Meanwhile, Phoebe, who hasn't heard from Cole since Belthazor's last attack, worries where he is. The sisters try to bless the potion, but it doesn't work because they forgot to add the critical ingredient, the piece of Belthazor's flesh. Piper adds the flesh to the pot and the potion explodes, knocking her across the room.
Belthazor hides in a cemetery from the demonic bounty hunter Krell, who is after him because he has killed the Triad. Belthazor is still bleeding from when Piper gashed off his flesh. Krell finds some of Belthazor's blood and tracks him to a mausoleum. Krell throws lightning at Belthazor, but Belthazor dives out of the way and throws an energy ball at Krell. The energy ball knocks a column onto Krell, giving Belthazor time to escape. With some difficulty, he turns into Cole and joins a nearby funeral, hitching a ride with a mourner and eluding Krell.
Phoebe plans to go to Cole's office after class. Prue thinks Phoebe has forgotten about Belthazor, and in any event, thinks Phoebe is only setting herself up to be hurt. Phoebe borrowed Prue's car yesterday and tried to find Cole at his apartment, and all she got for her trouble was a parking ticket. Prue has written a spell to summon Belthazor so they can vanquish him; it doesn't require the Power of Three. Piper gives Phoebe a bottle of vanquishing potion just in case Belthazor attacks her while she's out.
Cole hides in an alley and tries to use his shirt to staunch the blood. His human form is too weak to rip a rag off the shirt, so he turns into Belthazor and rips the shirt in half. He abandons his coat, where a homeless man finds it.
As Phoebe goes to class, Prue and Piper duck behind an overturned table and chant the summoning spell. They end up summoning Krell instead. Krell tries to blast Prue and Piper, and he only manages to blow a hole in the table. Prue sends Krell flying, but Piper freezes him in midair before he hits the grandfather clock. Piper thinks they have the wrong demon; as far as they know, Belthazor normally doesn't have a human form. Prue thinks Piper should unfreeze only Krell's head so they can grill him. Piper hasn't tried this before, but to her surprise, it works. Prue demands to know who he is, but Krell threatens to kill Prue and Piper unless they unfreeze him. Piper obliges and Krell flies into the grandfather clock, smashing it. Prue kicks him in his back and demands answers from Krell. Krell explains that he, too, is after Belthazor.
Phoebe goes to Cole's office and finds Reece Davidson, an investigator with the DA's office, in his chair. Reece informs her that he's also looking for Cole. When Phoebe mentions that Cole was working on a big case, Reece tells her Cole hasn't worked on any cases during his stay at the DA's office. After being grilled on Cole's whereabouts, Phoebe leaves for Cole's apartment.
Krell explains that he intercepted Prue and Piper's summoning spell because he isn't powerful enough to vanquish Belthazor, even though Belthazor is so weak he can't shimmer. Prue thinks the Triad passed the contract on them to Krell, but Krell tells them that the Source sent him after Belthazor for killing the Triad. He suggests that they work together to find Belthazor. Piper doesn't like this idea at all. Krell says that they have no choice, since the only way Belthazor can save himself is by killing them. Prue and Piper call for Leo; they want answers.
At Cole's apartment, Phoebe notices drops of blood on the carpet, and enters and finds the wounded Cole. As he refuses to go to a hospital, Phoebe tries to call for Leo, who does not answer. Phoebe returns to the manor to find Leo, promising Cole she'll bring him back to help.
Piper is upset that Leo didn't know the Triad was dead, but Leo says he thought it was only a rumor. Piper still doesn't like the idea of working with a demon, but Prue thinks it's the only way to get Belthazor off their backs. Leo sides with Prue, much to Piper's disgust. Prue and Piper try to summon Belthazor again, and Krell intercepts it as before. Just as Krell appears, Phoebe comes in. Thinking it's an attack, she rushes at Krell and kicks him. Prue and Piper fill Phoebe in. Krell has picked up Belthazor's scent again. He suggests that one of the sisters go to the cemetery; if Belthazor is hiding there, Krell won't be able to track him due to the large amount of evil there. Phoebe offers to go to the cemetery but as Prue and Piper are leaving, fills in Leo about Cole.
Instead of going to the cemetery, Phoebe brings Leo to Cole's apartment and begs him to heal Cole. When he does, he is blown backwards from the resulting blast. Cole is out of immediate danger. Leo informs Phoebe in private that he only healed part of Cole. Since he can normally heal mortals completely, Leo suspects Cole is at least half demon, and might very well be Belthazor himself. Phoebe doesn't want to believe it, but Leo points out that Cole's wound is in the exact same place where Piper gashed off some of Belthazor's flesh. Leo doesn't want to leave Phoebe alone with Cole, but Phoebe isn't worried; she has the potion just in case. Leo orbs out.
Krell leads Prue and Piper into the alley. They find the homeless man, covered in Cole's coat. Krell thinks he's the human form of Belthazor. Krell snatches Piper's potion and throws it at the man, but nothing happens. Krell grabs the man and starts to torture him with lightning, but Prue knocks Krell's legs out from under him. Prue initially thinks Phoebe can get a premonition off the coat, but then remembers that Cole had a coat exactly like this one. She suspects that Cole is Belthazor.
Cole is washing up in the bathroom while an increasingly suspicious Phoebe looks around. She finds his briefcase empty and his drawers empty except for a pencil. She pulls the potion out of her bag.
Prue, Piper and Krell come to Cole's apartment. Leo orbs in; he's about to tell Prue and Piper his suspicions when Prue breaks in and says she's convinced Cole is Belthazor.
Phoebe thinks Cole is hiding something, and has the potion behind her back. Just as she asks Cole who he is, Prue, Piper and Krell bursts in. As Phoebe looks on in horror, Cole turns into Belthazor and pulls an athame on her. Krell tries to blast Belthazor, but Prue, fearing for Phoebe's safety, knocks his hand out of the way. Belthazor shimmers away. Krell thinks Belthazor is only using Phoebe to get at Prue and Piper. He offers to save Phoebe, if it's what it takes to kill Belthazor. Krell takes a potion bottle and shimmers after Belthazor. Prue and Piper, however, suspect he might try to take a run at Phoebe, and they secretly follow him.
Belthazor and Phoebe shimmer to the cemetery. Phoebe elbows Belthazor in the stomach and throws him over her shoulder. Just as she's about to throw the potion, Belthazor turns back into Cole. Phoebe is still determined to vanquish him, but Cole begs Phoebe to spare him. He confesses his attempts to kill them, but couldn't because his love for Phoebe reawakened his human half. To show Phoebe that he means it, he offers himself to be vanquished, but before Phoebe can do so, Krell shimmers in and blasts Cole to the ground with lightning. Cole and Phoebe retreat into a mausoleum. Krell prepares to throw the potion, but Phoebe knocks the potion out of his hand and kicks him. They fight, and Phoebe seems to be getting the better of it when Krell shimmers out--and shimmers back in behind her. He's about to blast Phoebe when Cole vanquishes him with an energy ball.
Piper and Prue enter the cemetery, calling for Phoebe. To save Cole's life, Phoebe has him drip his blood on his shirt, then throws the potion on the shirt. Piper and Prue console Phoebe for having to vanquished her lover, unaware of the truth, which the guilt-ridden Phoebe keeps to herself.