The sisters are outside admiring an aurora borealis (something not usually seen in San Francisco). Piper stands up and passes out, and Leo can't help her. The others get her to the hospital. She has toxemia. The doctor orders her on a no-salt diet and bed rest. Leo speculates that this is a state of mind, and that's why he couldn't heal her.
Gifts from magical beings pile up, and Paige and Phoebe find a unicorn in the kitchen, they find a present tag, from El to them. Presumably, the Unicorn bit part of the tag off and so they don't know who it is, possibly someone from Spain. Paige tries to orb it out, but can't. Phoebe tries a spell and it doesn't work. Leo can't orb to the Elders. None of their powers work. The Book of Shadows is blank. They try to keep the news from Piper.
Stanley shows up at the manor and tries to attack Paige with a fireball, but the fireball fizzles. He attacks her physically, and Phoebe kills him with a carving knife. She and Paige frantically hide the body when Victor shows up to present them his new wife Doris.
Cronyn arrives at the manor and asks the sisters to help him save magic. He notes that both good and evil magic beings have lost their powers. Paige is skeptical, but Phoebe wants to meet with Cronyn. They agree to meet in a pizza pub. Piper suspects something is up and that the others are hiding something. Leo ushers Victor and Doris out of Piper's room and spills the beans. Piper gestures but Leo doesn't blow up. Right afterwards, Piper's water breaks six weeks early.
At the meeting with Cronyn, Paige and Phoebe find themselves surrounded by demons, but they have come prepared with improvised weapons and a smoke candle, as well as the usual combat skills. Cronyn walks away as the fight continues.
Leo goes to fetch the other sisters, and then Doris stabs Victor with the knife without anyone knowing. She is now alone with Piper. The other sisters interrogate a demon and realize that Cronyn is after Piper's baby. They rush back to the manor. Cronyn gets there ahead of them and Piper is now in labor. Paige scrapes a bit of dust off the unicorn horn. Cronyn hears the unicorn's neigh and goes to investigate. Piper bashes Doris over the head and escapes, still in labor. Cronyn and Doris catch her on the stairs.
Phoebe and Paige come from the basement, where the unicorn is tied up, and confront Cronyn and Doris. Victor comes to and pushes Cronyn away from Piper. Paige throws the unicorn dust and she and Phoebe say the vanquishing spell.
Piper gives birth under light coming from the chandelier above, and to everyone's surprise, the child is a boy.