Phoebe has been shot for parking in Mrs. Noble's driveway, but Leo heals her in time. Leo explains that Gideon messed up the cosmic balance when Phoebe and Paige went to the evil world and their evil opposites didn't come through. As a result, their world is now too good; every little infraction is a capital offense. Phoebe and Paige go to the hospital to join Piper. Leo goes after Gideon. Chris stays behind to watch Wyatt.
Gideon goes to Barbas and claims that Wyatt is a threat to both of them. Gideon says that a great evil must corrupt the good world to restore the balance. He offers to do this if Barbas will keep the Charmed Ones distracted.
One of Leo's fellow Elders finds Leo trying to sense Gideon. The Elder tells Leo that while many of them shared Gideon's concerns about Wyatt being too powerful, Gideon should have never acted alone. He warns Leo that he risks doing further damage if he goes after Gideon alone. However, Leo is determined to hunt down Gideon himself. Phoebe and Paige enter the hospital and find lots of patients with severed limbs as punishment for minor offenses. They also notice that the sun never sets in this world. Piper has been affected by the cosmic shift and seems quite cheerful in spite of being in labor. Phoebe and Paige try to tell Piper that Gideon is the one after Wyatt, but Piper scoffs. Piper's contractions get stronger, and a doctor hustles Phoebe and Paige out. Barbas has slipped into the hospital, disguised as an orderly. Gideon orbs in and suggests playing to Piper's fear of losing her sisters.
Chris scries for Gideon, but can't get a fix on him. He suggests that Leo bust himself back down to Whitelighter again once he goes back to his world--but he isn't leaving until after he figures out why Wyatt turned evil. Leo and Chris realize almost at the same time that Gideon's concerns about Wyatt were actually a self-fulfilling prophecy. Leo suspects that in Chris' future, Gideon took Wyatt away for several months and tried to kill him. He also thinks that the shock of having to constantly defend himself at such a young age was what turned Wyatt evil.
At Magic School, Phoebe and Paige try to contact their evil counterparts. They hear an echo, and discover their evil counterparts are trying to contact them as well, through the mirror. Evil Phoebe and Paige report that their world has become entirely too evil, just like the normal world is too good. Every good deed is an offense worthy of losing a limb or worse, and it's always night. The Phoebes and Paiges think that if they can snap their Pipers back to themselves and get the evil sisters in the good world, they might be able to shift the balance back.
Barbas gives Piper a vision of Paige and Phoebe being vanquished by the Elders for speaking ill of Gideon. She casts a spell, and now Phoebe and Paige are as excessively cheerful as everyone else. Instead of going after Gideon, they are going to attend the birth of baby Chris (whose name is revealed to be that of Leo's father). Leo and Chris suspect that Gideon somehow made Piper cast the spell to throw them off his trail. When Chris tries to tell them that Gideon might take another run at Wyatt, they laugh at the idea. Darryl shows up to arrest Chris for assaulting him. Phoebe and Paige don't bother to back Chris up,instead encouraging his arrest, forcing Chris to blow Darryl out the door.
Leo goes to the hospital to ask her if she'd seen him. Leo learns that there is a complication in Piper's delivery and rushes to her aid. Barbas, at Gideon's suggestion, gives him a vision of Wyatt morphing from a small baby to a full-grown man, the evil Wyatt that Chris was trying to stop. Wyatt orbs Excalibur into his hands and stabs Leo.
In the attic, Chris hears the footsteps of an unseen figure. He moves to flee with Wyatt but the figure flings him back, it's Gideon. Gideon becomes visible, armed with a knife, then goes invisible again. Chris rushes toward Wyatt, but Gideon reappears, stabs Chris and orbs away with Wyatt just as Leo comes to Chris' aid. Gideon orbs Wyatt to Barbas's lair just as Leo arrives. Barbas lunges to stab Wyatt but he orbs away. They plan a way to track Wyatt and kill him. Leo tries to heal Chris, to no avail. He doesn't want to leave Chris alone so he kisses Chris on the forehead and orbs back to the hospital to get Paige and Phoebe so that one can keep an eye on Chris. They still don't believe that Gideon is out to kill Wyatt, but when Leo tells Paige and Phoebe that Chris is dying, the news breaks Piper's spell, allowing them to remember what is happening. Paige orbs to the manor but is greeted by a SWAT team, Darryl and Inspector Sheridan. They demand that she turn in Chris. Paige refuses and Sheridan knocks her to the floor with a back-handed slap.
Good Leo meets Evil Leo at Gideon's mirror. They realize that Gideon is hiding in the underworld, and that Barbas is working with him. Wyatt is orbing all over the underworld and vanquishing demons with little more than a glance. Barbas is hot on his tail. A teary-eyed Paige calls for Leo. When he gets there the SWAT team and Inspectors Sheridan and Morris come out of the room that Chris is in. When Leo asks what they're doing there Sheridan simply responds, "Nothing, we didn't have to." Leo looks at her confusedly. Darryl adds, "I'm sorry, Leo." Leo runs into the room to see that Chris is very weak. He asks him to hold on and not to give up. Chris responds with a weak, "You either." Then his head falls back on the pillow and he dies. His body fades away.
Leo trashes the attic in anger, but Paige calms him down. He realizes that Gideon is using Barbas to commit an act of great evil. Paige suggests that Leo intercept Gideon's call for Barbas.
Gideon lures Wyatt by using Leo's voice and catches him in a crystal cage. Barbas walks in to witness Wyatt's death. Just as Gideon raises his athame, "Barbas" grabs it and stabs Gideon. "Barbas" turns out to be Leo in a glamour. Leo sends Gideon flying across the cavern. Gideon protests that he was only acting out of concern for the greater good. Leo retorts that killing a child is never in the interest of the greater good and that Gideon has no right to decide that unilaterally. He calls the mirror where evil Leo and Gideon are waiting. Good Leo starts blasting Gideon with electricity.
In the hospital, a surgeon cheerfully informs Phoebe and Paige that Piper is hemorrhaging. When Phoebe demands that he go back into the operating room, the surgeon calls for security. As the guards approach, the world starts to change. The happy, sunny scene gives way to nighttime; everything is back to normal. The confused surgeon promises to do what he can.
Gideon is electrocuted by Leo, finally stating that Leo doesn't know what he's doing. In death Gideon crumbles to dust. The two Leos smash Gideon's mirror so their worlds can never cross again. Leo takes Wyatt and heads for the hospital. At the hospital, Phoebe, Paige, Leo and Wyatt see a healthy baby Chris, and are relieved to find out that Piper made it. Leo goes in to see Piper and takes baby Chris along with him. The doors to the recovery area close, magically or at least automatically.