Piper has made a batch of wheat germ pancakes, but no one appears interested in having one. Just as she carries the plate behind Paige, Cole waves his hand, popping up Paige's bagel and causing Piper to drop the plate. The commotion unnerves Phoebe, who is on a deadline. Just then, her laptop's battery dies. Cole glances at the smoke alarm, causing it to go off; Leo hovers to turn it off. Cole tells Phoebe that they can have all the quiet they want if they get their own place.
Leo is exhausted; ever since the sisters vanquished the Source, he's been getting more work than normal. The Elders want him to check out Maria, a high school teacher who has been identified as a future Whitelighter. Piper tells him that she plans for them to attend a reunion of veterans of the Battle of Guadalcanal, telling the organizers that Leo is his own grandson. Leo in fact died at Guadalcanal. Leo isn't happy; he does not want to be seen there. He abruptly orbs out.
At the area VA, two ghosts, Rick and Nathan Lang, who were close friends of Leo and who also died at Guadalcanal, blame Leo for their death. Once they find out his "grandson" is attending, they scare the secretary out of the room so they can find out where the "grandson" lives.
Piper wants to talk to Leo, but he isn't answering her calls. Paige is looking for her keys, when she sees Nathan standing in the stairway. Nathan is surprised that Paige can see him. Piper walks in just as Nathan disappears. Piper doesn't think the ghost can possibly be good, so she wants to check out the Book of Shadows. However, Paige wants to check out the Book herself; it's the first time she's seen a ghost that isn't related to her.
Nathan returns to the VA and tells Rick that Leo's "grandson" is married to a witch--and his two sisters-in-law are witches as well. He thinks they may be in over their heads, but Rick is determined to get revenge. Rick smashes Leo's picture to the ground. Nathan wonders how Rick did this, and Rick tells him that his hatred for Leo allows him to regain a sort of physical form. To prove it, he's fully corporeal just as a guard walks in. Rick grabs a bayonet and runs the guard through. He tells Nathan to focus on his anger at Leo, and Nathan is corporeal as well.
Cole interviews a pretty blonde woman, Julie, to be his personal assistant. Julie turns out to be a fellow demon. Cole wants Julie to help him separate Phoebe from her sisters. He decides to put her through a trial run by having her cover for him at the office while he messes with the power at the manor. Julie subtly hits on Cole.
Leo talks with Maria while fixing her sink. Maria is distraught over having to suspend one of her students for pulling a knife, and he's threatening to come after her. She's thinking of quitting. Leo talks her into staying on, since she has the chance to do more good.
The sisters find the spell and potion to vanquish ghosts ("The Power of Two"). Piper notices Leo's medal of honor from Guadalcanal; he hid it away in his army file. The power goes out, causing Phoebe to lose half her column; she muses about getting her own place. Phoebe calls Cole to let him know what's happening--and Julie answers, claiming not to know Cole is married. Julie says Cole isn't in the office, but Phoebe says she really needs to talk to him. Unknown to the sisters, Cole is in the basement--he's the one who tripped the breaker. He flips the power back on and flames out. Julie pretends to be Cole, copying his voice while talking to Phoebe, who is concerned she'll miss her deadline. Julie says that there's a place Phoebe can work just as Cole comes back and takes the phone. He suggests the towers near the ocean, where his firm is having a party tonight. Cole tells Julie that she's hired.
Paige finds Rick and Nathan in an old picture with Leo, and wonders if they're the ones who cut the power. Piper finally gets Leo to orb in. He recognizes Rick and Nathan in the picture, but doesn't want to talk. Just then, Rick and Nathan come through the wall. Rick throws a knife at Leo. The wound heals itself. Rick and Nathan disappear.
Leo tells Piper and Paige that he and the Langs grew up together in Burlingame, a suburb of San Francisco. They enlisted together, and their unit ended up fighting in Guadalcanal. Nathan was badly wounded, but their unit was under heavy fire and there weren't any medics out in the field. Leo ran out of the tent, and literally seconds later, a bomb hit it and killed everyone in it. Had Leo been in there, he would have died as well--along with all the other troops he'd saved. The Langs have been carrying their anger for years, and it's keeping them from moving on. Leo doesn't think he deserves to be a Whitelighter, since he let his friends die. The sisters plan to summon Rick and Nathan from the grave so he can talk to them and explain why he left the tent.
Rick and Nathan realize that the "grandson" is Leo himself. Nathan, however, sensed Leo's guilt over leaving them behind. Rick wants to kill him, but Nathan reminds him that they can't, since he's a Whitelighter. Instead, they plan to kill those closest to Leo.
Cole shows Phoebe the apartment his firm is using for the party that night. Phoebe sounds more receptive to getting a place of their own. Cole heads back to the elevator. Julie is waiting for him, and helps Cole pick a dress for Phoebe to wear at the party. Julie tries to hit on Cole again, but Cole rebuffs her.
Paige finds out the Langs were buried at the VA. She, Piper and Leo are about to head there when Leo gets a jingle--Maria's in trouble. Unknown to them, the Langs are listening in, and see a chance to get under Leo's skin. Leo arrives to find Maria being threatened by Greg, the student she suspended earlier. He has her at knifepoint, but Leo and Maria talk him into dropping it. Just then, Rick appears and stabs Maria. Leo tries to go to her, but Nathan grabs him. Leo tries to heal Maria, but her spirit has already left her. The Langs tell him that she was an innocent whose blood is now on his hands--just like theirs.
Piper and Paige are about to head to the VA, when Phoebe comes down in a long black dress. Piper and Paige tell her that the Langs tried to kill Leo. Phoebe is about to call Cole to back out of the party, and mentions that she and Cole are getting their own place. Piper tells Phoebe to go on to the party. Piper's feminine intuition tells her that Leo is in trouble. Paige uses her sensing power to find him, and confirms that something is indeed wrong. Paige orbs to Maria's place to find Leo crying over Maria. Leo tells Paige that the Langs killed her to get even with him for leaving them to die. He also says that he's lost his powers, and doesn't deserve them in the first place. Paige tries to convince Leo that he is not responsible for what the Langs are doing. Realizing that he's defenseless without his powers, she orbs out to get Piper and Phoebe. The Langs are listening in the whole time. Rick wants to kill him, but Nathan wants to make him suffer first.
Cole and Phoebe are dancing at the party, when Paige orbs in to warn Phoebe about Leo. Cole lets Phoebe go.
Piper is making the potion when Rick appears and throws a knife at her. She freezes it in midair, but Nathan appears behind her and stabs her. Rick covers her mouth and squeezes her heart until she stops breathing. Paige and Phoebe arrive, and try to revive Piper with no luck. Leo runs in; he was looking for Rick and Nathan. Just then, the Langs reappear, and Nathan knocks Leo to the ground. Paige leaps at Rick, but he goes invisible and she lands on some boxes. Paige tries to get up, but Rick slaps her down. Leo begs the Langs to come after him. As they're roughing him up, Piper's spirit leaves her body. Remembering the spell, she has Phoebe and Paige grab the Book. Piper speaks the spell just as Rick is about to stab Leo, and the Langs are vanquished. Piper's spirit starts floating away. Paige reminds Leo of all the lives he's saved. Leo gets his powers back, and heals Piper.
Phoebe comes back to the apartment; the party's long since ended. Cole tells her the firm has offered them the apartment, and it's theirs for the taking. With Paige's new control over her orbing making it easier for her to reach the manor from a distance, Phoebe agrees.
Piper and Leo attend the reunion. Leo meets several people whom he saved on the battlefield, including the man he died saving. The man waves over his son and grandchildren to introduce them to the "grandson" of the man responsible for them being born. Piper looks on proudly as Leo is introduced to all the lives who only exist because of him.