A man orbs into the manor; Paige orbs a lamp at him, but he catches it, identifies himself as Simon Marks, and claims to be Paige's future husband. He claims that the Marks and Warren families worked together during the Salem witch trials, and that 40 oracles and soothsayers had predicted his marriage to Paige, "plus a wizard or two". Paige tells him of Henry and Simon makes fun of Henry, always calling him "Harry". Simon orbs to Piper and tries to state his case, but she tells him off. Backing out of her parking space, she bumps her car into that of Greg, her former beau last seen in "I Dream Of Phoebe".
Billie tries to talk Christy into telling her who's coming for her. Paige tries to compile a list of possible demons. Henry comes to the door and Paige tries to wave him off, but Henry refuses to run away. Christy has a panic attack, and then strangely gains composure, saying "they" are coming now. Billie and Christy come downstairs and warn the Charmed Ones, as three demons shimmer in. Henry is wounded. Christy is revealed to have the power of Pyrokinesis. Paige heals Henry, who reluctantly agrees to leave.
The surviving demons summon the Triad, the supreme evil. The demons had held Christy for them, and all the demons want Christy back. Greg appears at the manor, offering Piper a deal to get their cars fixed cheaply. Simon orbs in behind his back and mistakes him for Henry. Paige throws Simon out. Piper feels guilty, but leaves with Greg.
Simon orbs into Henry's office, and they meet over lunch. They argue over Paige, and at last Simon conjures a glove, slaps Henry with it, and pompously challenges Henry to a duel.
Henry calls Paige and asks what she knows about duels. Phoebe and Paige find Billie on fire; Christy had attacked her and left with a demon. Paige orbs her jacket away. Christy had heard voices calling her the key to the ultimate power. Phoebe says that Christy had contacted the demons, as they were all she knew; Billie doesn't believe this.
Billie senses Christy's call, but Phoebe and Piper suspect a trap. The witches reverse the call-a-lost-witch spell and Billie finds herself in the demons' lair in front of Christy. The demons appear and Billie appeals to Christy. Christy, at last, conjures a huge fireball, which combined with Billie's projection power, destroys the demons. Phoebe and Piper undo the spell and Billie and Christy return to the manor. She orbs and finds Simon thrashing Henry by using telekinesis to hit him with a metal rod. At last, Henry tells Simon off, because he actually cares about Paige, whereas, Simon just wants a trophy witch. Paige also tells Simon off, giving Henry a window of opportunity to punch him and knock him down, and at last Simon concedes and orbs away.
Piper tells Greg that Leo is coming back. Paige orbs Henry to the top of the Golden Gate Bridge, which has become their "place". Henry proposes marriage, and Paige accepts.
Christy finally opens up to Billie. They look through old pictures from before Christy was kidnapped. Christy says that she was being brainwashed and the demons made her attack Billie. Billie promises not to let anyone harm her. Phoebe is eavesdropping, but Piper chases her away.
At Magic School, the Triad announce that Christy is in position.