Leo and Piper host a birthday party for Wyatt. Afterwards, Piper notes the champagne (The Elders aren't allowed to drink), chocolate-covered strawberries and oysters on one of the tables -- clearly not meant for the kids. Chris tells Phoebe and Paige that he must be conceived today or he ceases to exist. Phoebe suggests telling Leo and Piper the truth.
A Darklighter, Damien, orbs in and is apparently after Leo or possibly Wyatt. The others come in and the Darklighter shoots at Leo, who orbs out in time. Phoebe pushes Chris out of its way and Paige orbs the arrow back into the Darklighter, who orbs away wounded. The leader of a gang of Darklighters removes the arrow and Damien survives. The leader orders the Darklighters to distract rather than harm the Charmed Ones.
Gideon warns Leo to cut all family ties, as fatherhood has distracted him from his duties as an Elder and put him in danger.
Phoebe starts scrying for the Darklighter and the scrying crystal flutters strangely. Believing that there is more than one Darklighter, Paige and Phoebe go with Piper and Leo after the Darklighters. Phoebe falls off a roof during the fight and goes to the hospital afterwards. After the sisters vanquish several Darklighters, one appears behind Leo and Piper. Piper blasts him -- and she and Leo apparently disappear in the explosion.
Leo and Piper find themselves on an empty street with only themselves and Damien. They flee. They go to the hospital, expecting to find Phoebe, but find only an empty building. Leo briefly saw the ghost of a bus driver being treated in the hospital and realizes they're on the ghostly plane. The ghost saw Leo and spoke that name when revived. Paige and Phoebe check the Book of Shadows regarding ghosts.
Chris is starting to fade away. He appears transparent. An angel of death calling himself Clarence appears to him. As Paige and Phoebe use a seance to try to contact Piper and Leo, Chris disappears altogether and finds himself in the ghostly realm, and sees Piper and Leo there. In the next moment he fades back to the real world and tells Paige and Phoebe what Leo and Piper think: that the Darklighters used some kind of portal.
Darklighters attack both the real and the ghostly manor, and Leo is hit. Leo and Piper talk, and then make out and conceive Chris.
Paige and Phoebe go to Gideon and ask him to help them reverse the Darklighter's portal. Gideon says Darklighters don't have the power to make portals, and shows them a page about portals in a large tome.
Leo and Piper return to the point where they enter the ghostly plane. Damien tracks them there, and takes aim at Leo. In that moment, the three find themselves back in the real world. Paige and Phoebe confront Damien, but the leader shoots him from a rooftop. Chris becomes solid again. Leo collapses from the Darklighter poison in his wound, and Paige orbs him and Piper to Gideon.
Leo is meditating atop the Golden Gate Bridge and Gideon orbs to him. Leo says he cannot justify staying on Earth any more.
Clarence tells Chris he's been given a second chance.
Phoebe and Paige tell Piper, "We know what happened between you and Leo last night". They finally tell Piper that Chris is her son, but Piper denies being pregnant at first. But the possibility eventually strikes her. Chris walks in, and Piper gives him a long stare.
The Darklighter leader meets with Gideon, who assures him that Leo is now gone. Gideon says that allowing Wyatt to be born, to allow such a huge concentration of power to manifest in one being, was a mistake; one he intends to correct.