Set in the 24th century, the series follows the adventures of the crew of the Federation starship USS Enterprise-D. In this episode, an Enterprise crewmember is killed in a tragic accident, leaving a newly orphaned young son to deal with her death.
The crew continues to investigate the planet, discovering several more mines that were recently unearthed and exposed, possibly on purpose. They observe a beam of charged particles emanating from the surface headed towards the Enterprise, while Counselor Troi (Marina Sirtis) senses a new presence from the planet. In Jeremy's quarters, a physical manifestation of Marla appears, explaining that the crew mistakenly considered her dead and offering to take Jeremy to live on the planet. Troi, sensing the presence's arrival on the Enterprise, follows the two along with Security, preventing "Marla" from using the transporter to return to the planet. They return to Jeremy's quarters, which have taken the appearance of the Asters' home from Earth. Chief Engineer La Forge (LeVar Burton) tunes the shields to stop the particle beam, causing "Marla" to disappear and the room to return to normal.
A filament rises from the planet, striking the Enterprise and disrupting the shields; "Marla" again appears and takes Jeremy, intent on going to the transporter room. Picard orders "Marla" to be contained by force fields and then arrives to talk to her. "Marla" explains that she is one of two races that once lived on the planet below; her species, made from energy, watched the other physical species wipe themselves out from wars and wanted to prevent more suffering; thus, after Marla's death, these aliens mollified Jeremy with the illusion of his mother still being alive. Picard and Troi point out that dealing with death is part of the human condition. Wesley explains to Jeremy how he dealt with the death of his own father. Jeremy expresses his hatred of Worf, but Troi points out they are both orphans, while Worf notes that he was aided by humans after he lost his parents. Jeremy decides to go with Worf; the illusion of Marla returns to the surface peacefully.
Some time later, Worf and Jeremy undertake the R'uustai and honor the memory of their mothers.