The station is near Klingon space, and a Klingon commander, Morag, is cited in Aquiel's logs as repeatedly harassing the station - a situation which added tension to an already chilly relationship between Aquiel and Rocha. Picard, seeking to cover the Klingon angle, speaks to the local Klingon governor, Torak, and through veiled threats about bringing Gowron in to examine Torak's work, manages to convince Torak to help with the investigation. However, when Torak's ship arrives, the investigation is thrown into an uproar - for on board is Lt. Aquiel Uhnari, very much alive.
Aquiel claims that Rocha suddenly attacked her for no reason, and that she remembers nothing after the attack. Meanwhile, as new evidence showing a Klingon presence on the station comes to light, Picard demands to be allowed to speak to Morag about his involvement in the matter; Torak grudgingly agrees. As work continues on analyzing the cellular residue, now expected to be Rocha's remains, Geordi and Aquiel start forming a close friendship, despite (or perhaps because of) Geordi admitting to advance knowledge of her through her logs.
A search of Rocha's record turns up a spotless and bright career, and a similar search of Aquiel's file shows an argumentative, difficult officer. In addition, a search of Aquiel's shuttle reveals the missing phaser from the station's weapons locker, set to a level high enough to kill. Riker and Worf confront Aquiel with this information, but desist when she protests innocence and Geordi defends her. All agree to wait for Morag's imminent arrival, but Riker strongly suggests, off the record, that Geordi distance himself somewhat from Aquiel until the situation is understood.
Morag arrives, and admits to boarding the station when hails went unanswered. Under further pressure, he admits to covertly obtaining some coded messages, but claims to have killed no one. Picard orders that he remain aboard. Meanwhile, however, Geordi finally gains access to Rocha's logs, only to find several missing. He discovers that Aquiel erased those logs because they contained a harsh letter to Starfleet about her attitude, and points out that she's digging herself in deeper by destroying evidence. He convinces her not to run, and they become romantically involved. She invites him to join her in a rite that increases intimacy for her species, and he joyfully accepts.
Dr. Crusher's analysis of the cellular residue reveals something startling: it is not from Lt. Rocha at all. Rather, it is a peculiarly structured DNA typical of that of a "coalescent organism", an organism that consumes, then becomes, new bodies periodically to survive. The conclusion she and everyone else reaches is that "Rocha" was in fact a coalescent by the time he arrived on the station, and that he attacked Aquiel to get a new body. They conclude that either Morag or Aquiel is currently the same coalescent, and put both under close examination, ruining Aquiel's rite with Geordi just in time. Geordi, bitter over what he sees as unfair treatment of Aquiel, rests in his quarters - but quickly finds that the coalescent is in fact Aquiel's "dog", Mora. It attacks him and attempts to absorb him, but he destroys it just in time. Her name cleared, Aquiel heads to starbase 212 for reassignment, thinking that she might put her name on the long waiting list for a position on the Enterprise.