Piper is being attacked by a Harpy in the manor. Phoebe and Paige orb in, and the sisters destroy the Harpy with a spell. Not before Phoebe is scratched on the shoulder. The sisters are glad they can still get the best of demons even though Phoebe has moved out of the manor. Paige offers to orb Phoebe back home, but Cole doesn't want Paige or Leo orbing in except in emergencies. Paige is still suspicious of Cole, but Piper still won't hear of it.
Cole is trying to end the infighting among the numerous demon and warlock factions prior to his formal coronation as The Source. He hears the elevator ding and abruptly adjourns the meeting. After the faction leaders blink, shimmer etc. out, he changes the meeting table to a dinner table. Phoebe steps out; Cole didn't expect her home this early. The next day, Phoebe is heading out after breakfast when Cole notices the scratch on her shoulder. Cole is concerned that Phoebe didn't tell him. Julie walks in on them kissing; Cole's working at home today since his office is being painted. After Phoebe leaves, Cole orders Julie to bring the Harpy leader before him; he wants to dress her down for allowing one of her minions to attack his wife.
The Vampire Queen plots to take on the new Source along with Keats, a demon who wants to overthrow Cole. The vampires have been exiled from the Underworld for decades, and the Queen first wants to see if Cole will give them amnesty in return for their loyalty. She sends her top lieutenant, Rowan, to Cole in hopes of ending her people's exile.
The Elders have noticed a spike in demonic activity, and want Leo to get a fix on it. Piper and Leo haven't had any luck conceiving, and Piper wonders if they'll ever be able to have a baby. Paige reassures her.
Julie brings back the Harpy leader's severed hand and tells Cole she won't be coming to see him; it is not known whether the harpy leader survived. She ushers Rowan in, but Cole barely lets Rowan get two words in before rejecting the Queen's offer. Paige orbs in to talk to Phoebe, and Cole isn't at all happy. Cole and Paige have a brief exchange of words. Paige's suspicions about Cole grow stronger. Paige bumps into Rowan in the elevator; they share a mutual distrust of Cole. Rowan asks Paige out as she leaves and they agree to meet at P3.
Rowan reports back to the Queen, who is pleased at the prospect of getting a Charmed One on their side. Keats is skeptical, but the Queen thinks that having the magic of even one Charmed One combined with theirs will enable them to take over the Underworld before Cole can consolidate his power. Rowan is running late; Paige thinks he stood her up. Phoebe comes in; she's concerned she may be getting sick from the scratch. She thinks she may be turning into a harpy, but Leo reassures them that a human can't turn into a harpy that way. He heals Phoebe in the office. Paige wants Phoebe to cheer Piper up about her pregnancy troubles, but when Phoebe finds out Paige orbed to the apartment she walks away in a huff.
Paige is walking to her car when a flock of bats swarm on her and attack her. She's bitten several times. At the hospital, the doctor tells Piper, Phoebe and Leo that Paige nearly bled to death. Paige initially suspects vampires, but Phoebe isn't sure; from what she understands vampires attack in human form. Leo adds that vampires have been banished from the Underworld for many years. Phoebe faints while the nurse draws blood from Paige. On the way back to the manor, she calls Cole on her cell phone and asks him to meet them there. Cole suspects the Vampire Queen is making her move, and orders Julie to gather the faction leaders for a war council.
The sisters can't get a fix on who attacked Paige. Paige assures Piper, Phoebe and Leo that she's fine, and heads to bed. Leo has found out that the recent spike in demonic activity is a sign that there's a new Source. Cole arrives, and the sisters tell him what happened to Paige. Cole thinks that biting bats could only mean one thing--Paige was attacked by vampires. Even though the previous Source banished vampires from the Underworld for selling him out, Cole dealt with them fairly often when he was Belthazor and knows how they operate. They run up to check on Paige, and find her hanging upside down in her room. Paige turns into a bat and flies out the window.
Phoebe and Piper grab a cross, a stake and some garlic while Leo scours for holy water. Piper has looked in the Book of Shadows about vampires, and has found out that vanquishing the Queen destroys the entire clan. However, they have to get the Queen before Paige feeds on someone's blood; if this happens, she will lose the rest of her humanity. Unfortunately, they need the Power of Three to vanquish the Queen. Cole initially does not want Phoebe to go, but Phoebe is determined to save her sister.
Cole flames back to the apartment, where the faction leaders (with the notable exception of the harpy leader) are already gathered. He considers the vampires' attempt to convert Paige as a personal attack against him, and orders all vampires hunted down and exterminated. Cole tells Julie that he won't shed a tear if Paige dies as a result.
Rowan brings Paige before the Queen. Paige is starving, so the Queen suggests she feed on her sisters. Rowan is ecstatic; he thinks Cole won't stand a chance against them with all three Charmed Ones on their side. Paige doesn't think it will be easy, but the Queen tells her the rest of her clan will help her out. Paige kneels before the Queen.
Keats is warning a vampire that Cole is on the warpath, not knowing that Cole followed him. The vampire turns into a bat and tries to escape, but Cole destroys him with a fireball and demands that Keats tell him where to find the Queen. Keats replies with an energy ball, but it doesn't even scratch Cole. Cole tortures Keats with fire, and Keats finally talks.
Paige and Rowan return to the manor, but it's deserted. Paige is now wearing a two-piece red dress, like most of the other female vampires. Rowan tells Paige about his many feedings. He also assures Paige that she was more than "fast food"-- apparently he led the flock of bats who attacked Paige earlier. He suggests that Paige use her new-found vampire powers to find her sisters. Paige finds them, and tells Rowan to tell the Queen she'll be back with her sisters in tow.
Piper and Phoebe are trying to track Paige down in the cemetery. Phoebe almost faints, worrying Piper. However, Phoebe tells her she took a pregnancy test, and it came back negative. Piper took one as well, with the same results. Phoebe realizes that's what Piper wanted to talk to her about, and reassures her she still wants to be part of the family. Just as they embrace, a bat alights on a gravestone and turns into Paige. Piper wants to take her home and brew up a potion to turn her human again, but Paige shoves her aside and goes in on Phoebe. Paige meets Phoebe blow for blow. Phoebe knocks Paige down, but Paige recovers and kicks Phoebe down. She's about to bite Phoebe when Leo orbs in and sprays holy water on her. Paige turns into a bat and flies away.
Leo, Piper and Phoebe orb to a nearby cave where they find the Vampire Queen, Rowan and Paige waiting for them. The Queen offers Piper and Phoebe a chance to be converted without a fight, but Piper will have none of it. The Queen calls down a swarm of bats on Leo, Piper and Phoebe. Leo fends them off with holy water, but Rowan sends him flying. Phoebe engages him, but Rowan quickly knocks her down. Paige is about to bite Piper and Rowan is about to bite Phoebe when an unseen force starts blasting the bats with fireballs. Unknown to them, Cole is personally hunting the Queen. Leo takes advantage of the distraction to pull Paige off Piper, while Phoebe gets out from under Rowan. The Queen senses Cole is nearby, and runs off with Paige. Phoebe has turned the tables on Rowan; she stabs him with the stake, vanquishing him.
Cole tracks down the Queen and flings Paige aside before vanquishing the Queen with a fireball. The vampires all go up in flames and Paige is back to normal. Cole is about to finish Paige off with a fireball when he hears Piper, Phoebe and Leo rushing in. Cole flames out. Paige knows that the Source was here but does not know he is Cole.
Paige tells Piper that she doesn't think it was a coincidence that she saw Rowan at Cole's place. Piper is more willing to listen. Between Cole not wanting Paige and Leo to orb in and his unwillingness to let Phoebe help them go after the vampires, she's starting to have second thoughts about him.
Phoebe gets a call from her doctor, who informs her that she is pregnant.