O'Brien is reunited with his wife, Keiko, and their two children. But during a celebratory picnic on a nearby planet, eight-year-old Molly falls into a vortex of swirling energy. When the rest of the crew arrives to help, they determine Molly slipped through a time portal that sent her back 300 years, to a time when the planet was uninhabited. They reactivate the portal and transport her out, but their calculations are off by a decade. When Molly materializes on the transporter pad, she is an 18-year-old woman.
Since she has been without human contact for ten years, Molly is like a wild animal, terrified of her parents and unable to speak. At Bashir's suggestion, a cargo bay is transformed with a tree, grass, and some boulders. There, the O'Briens begin the painful process of regaining their daughter's trust. When Keiko presents her with her favorite doll, Molly smiles for the first time.
Molly continues to make progress and learns to follow simple commands. She soon utters her first word — "Home" — and Keiko and O'Brien excitedly take her back to their quarters. When she shows them a photo taken at the picnic site, they realize Molly regards that planet as her home. Desperate to make his daughter happy, O'Brien recreates the spot in a holosuite. The plan works until the O'Briens must relinquish the suite to other customers. Scared by the hubbub of Quark's bar, Molly panics and stabs a customer with a broken bottle.
Sisko and Odo sadly inform O'Brien that Federation officials want Molly committed to a special care center. Knowing that forcing her to stay inside a confined facility over a long period of time will kill her, O'Brien plans to steal a runabout and take Molly to her planet. Once there, he will send her back through the time portal so no one will be able to find her. Although they will never see her again, O'Brien and Keiko know this is their only chance to save their daughter. However, they are caught before they can leave the station.
Odo comes to the scene and allows the O'Briens to proceed. They return to the planet, where they tearfully send Molly back through the vortex with her favorite doll. When Molly arrives, she recognizes her eight-year-old self hiding behind a boulder. Little Molly is frightened, but her older counterpart gives her the doll and sends her through the portal to be reunited with her family.