When Alan and Ann miss school, Serena goes to visit them at their apartment. She is attacked by the Doom Tree when she tries to peek into a secret room, but the aliens explain that it's just a botany experiment. Back at Raye's temple, the girls discover that Alan and Ann are really aliens by testing a twig caught in Serena's hair. Later, Serena runs into Darien outside of the apartment and tries to convince him not to visit. When he doesn't believe her, they end up going together. Ann traps Serena in the room with the Doom Tree and a cardian. When the cardian starts sucking Serena's life energy, the Doom Tree starts growing. Eventually, the tree engulfs the entire building. The other Sailor Scouts arrive outside and try to find a way to get inside and save Serena and Darien.