The sisters are in Magic School discussing how to kill The Source, who has recently come back to kill the sisters as a golem. They explain to Coop how they defeated him the last time; however, clearly it wasn't enough to kill him once and for all. Piper suggests using all the power of the white magic practitioners in the realm to destroy him. They suddenly hear violent thumps on the walls around them and find out that The Source is trying to break through the school's protective shield that wards off evil by firing multiple fireballs, however, it fails.
Piper insists that Paige orbs to every magical creature they have come across over the years, starting with Coop, and collect a bit of magic from each of them, thus making the strongest potion ever. She gives her the phosphorus cauldron that is able to collect large sums of magic.
Meanwhile, in the Underworld, Neena is preparing some kind of potion while Hogan is worried that he won't be able to get into The Source's inner circle. Neena has something bigger in mind and tells Hogan that The Source shouldn't trust them. The Source is still trying to get through the protection around Magic School while Piper tells Phoebe to go through every page of the Book to find a spell that can finally vanquish him and get him out of their lives once and for all.
Leo thinks Piper might be able to at least wound him with her new power, however, with him being made of stone, it's highly unlikely. She then gets an idea, and with Coop's help they beam back to the manor and she reveals Excalibur, which should be strong enough to wound The Source.
Paige is still collecting little bits of magic from every magical creature, including: a Mermaid, Fairy, Nymph, Leprechaun and a Unicorn. Paige also collects magic from Billie and tells her that they are grateful that she is there as a second line of defense if they fail. At Magic school, Phoebe is still studying the Book trying to come up with a vanquishing spell using bits and pieces from every page though she is skeptical of how she'll be able to do that. Leo encourages her, telling her that she's written hundreds of spells before and also tries to comfort Henry who believes that they might not be able to stop The Source. Coop and Piper beam back with the sword, and Piper insists that Leo takes the children somewhere safe and out of harm's way. By this time, Phoebe has nailed the new Source vanquishing spell after some encouragement. Neena and Hogan have nearly finished their own potion for The Source, as well, although Hogan is questioning the whole plan, and why she didn't kill any of the Charmed Ones' Innocents herself, which annoys Neena immensely.
The Source's attacks are now breaking through the protective shield causing rooms to catch on fire. The Charmed Ones hurry out their husbands and Tyler, who wants to stay and fight, until Leo convinces him to go. Just when they leave, The Source breaks into the school and Paige puts up her Orb Shield to protect her from any flying debris. Piper uses her new power to melt a rope that drops a chandelier on him, temporarily distracting him from Phoebe. She levitates and throws a potion at him, which gives Piper the opening to stab him with Excalibur. Paige throws another potion and they all hold hands. They chant the new Power of Three spell and Paige creates her orb shield again, protecting them from the now vanquished Source.
At that very moment in time, Neena casts a spell that gives her, as well as the horde of demons in her presence, the Vampire Queen and her subjects, and a mysterious man clad in black upon a rooftop, the Source's powers, making them extremely powerful. Still annoyed with Hogan, she puts an end to him once and for all, killing him with vines, which choke him to death. One of the demons asks Neena if she thinks they're going to follow her, questioning what she is exactly, to which Neena replies: "wouldn't you like to know."
Everyone goes to Piper's new restaurant and talks about being free from the Source finally. Grams appears and greets her grandchildren. They talk about when the little ones are going to come into their powers. Grams begins talking about how no matter what the Halliwell children are, whether it be part-Whitelighter, part-cupid, or full-blown witch, each member of the Warren line is special in his/her own way. Right on cue, Melinda attempts to reach out for her teddy bear, and, upon being unable to reach it, orbs it to herself, without anyone noticing.