“Aye, sir,” she said, then calmly set about her tasks. If there was one thing Krissten Richter had proved repeatedly over the past four years, it was that he could rely on her to keep her wits about her during a crisis.

Ezri’s eyes opened and she let out a long, forlorn wail. The sound pierced Bashir’s soul to its core. Above the biobed, a monitor confirmed that she was experiencing intense neurological trauma. Her nervous system was on fire, and he had no clue yet as to why.

“Get me the delta wave inducer,” Bashir said. “I want her unconscious.”

He pressed the wafer-thin device against Ezri’s temple, and she immediately relaxed. Her eyes closed and she grew quiet.

Please come back to me, Ezri,he thought as he lifted an exoscalpel from the instrument tray. He found himself staring at it as though he’d never seen it before. His hand felt unsteady, and recollections of his earlier near disaster with the instrument did nothing to calm him.

Don’t blame yourself, Julian,she had told him long ago, on a similar occasion. Back when she had been Jadzia Dax, and Verad Kalon had forced him to remove the symbiont from her body. Jadzia’s voice, weak and fading, spoke from his private citadel of memory: Don’t blame yourself, Julian. You did everything you could.

He forced himself to place that unhappy memory back on the high mental shelf to which he normally relegated such thoughts. He concentrated instead on trying to recall the particulars of every disease agent that might cause a spontaneous separation of host and symbiont. If one of these turned out to be the cause of Ezri’s condition, then a cure might already exist.

Hope buoyed him as he quickly adjusted his tricorder to look for particular genera of viruses and retroviruses.

Bashir’s combadge chirped before he’d completed a single pass with the device. “This is Merimark in the transporter room, Doctor.”

Damn!“Can it wait, Ensign?”

“’Fraid not, sir. Incoming medical emergency on the alien ship. I’m beaming possible wounded parties directly to the medical bay.”

“Acknowledged. Who’s coming?”

“It’s Nog and Shar, sir.”

When it rains, it pours,Bashir thought as he watched a pair of figures shimmer into view in the main medical bay chamber.

Bashir glanced toward Nog, who was propping himself up on his elbows, trying to get comfortable on the biobed. From his position, he couldn’t see the nearby bed on which Ezri lay unconscious.

Just as well,Bashir thought.

“I can’t believe this is happening,” Nog said, possibly for the hundredth time. He gritted his teeth as Lieutenant Candlewood checked the dressings on the stump of his left leg and made a quick tricorder scan of the rapidly healing—though still raw—wound that lay beneath.

Nog’s voice was flat and devoid of emotion. “I really can’t believe this is happening.”

Neither could Bashir. But the subject of Nog’s incredulity wasn’t his primary concern at the moment.

Ezri is.

She lay on the biobed between Nog’s and the one located in the medical bay’s farthest corner, on which the last of the convalescing aliens slumbered. Ezri’s breathing was ragged and shallow, and her pallor had increased hourly while she had drifted in an out of consciousness, confused and terrified during her few brief intervals of wakefulness. At least she was asleep at the moment, Bashir thought, without the need for the delta wave inducer. He was thankful for that one small mercy.

Krissten stood on the far side of Ezri’s biobed. “Dr. Bashir,” she whispered. “You’ve been… hoveringfor hours. Why don’t you get some rest? I’ll call you the next time she comes to.”

The medical bay doors hissed open before he could reply. Rubbing a weary eye with the palm of his hand, he turned toward the sound.

Commander Vaughn strode deliberately into the room, his craggy features solemn. Shar was at his side, his expression even more unreadable than usual, if that was possible.

Vaughn was first to speak. “Trying to communicate with the aliens has kept us a bit busy for the past few hours, Doctor. Sorry I haven’t had a chance to get down here before now.”

Bashir felt slightly muddled for a moment. Aliens? Then a glance at the long, spindly figure curled awkwardly on the third biobed brought him to alertness.

“Yes, of course, the aliens,” Bashir said at length. Now that he had released all of them except one, gravity in the medical bay had been adjusted back to its customary one gee, except for the immediate vicinity of the corner biobed. Krissten had made no secret of her delight at the return of Earth-normal gravity.

“Has anyone managed to translate their, uh, language yet?” Bashir asked.

Shar’s white dreadlocks, stark against his sky-blue skin, twirled slightly as he shook his head. “It’s hard to tell. But with Lieutenant Bowers and Crewmen T’rb and Cassini assisting me, I think we will manage it eventually. The alien text you downloaded may prove helpful in that regard after all.”

“Any change down here?” Vaughn said, looking in Ezri’s direction.

Bashir gazed at Nog and decided that any discussion of Ezri’s prognosis ought not to occur within range of the chief engineer’s sensitive ears. There was nothing to be gained by stressing him with bad news. Bashir gestured toward his office as Shar excused himself to speak with Nog.

“Give me the bad news first, Doctor,” Vaughn said, once the office door had closed discreetly behind him and Bashir.

“Ezri’s slipping away from us,” Bashir said. From me.He felt exhaustion suddenly gaining on him, with despair coming up hard on its heels. He sank heavily into the chair behind his desk.

“How?” Vaughn said, standing on the other side of the desk.

“There’s massive peritoneal inflammation in and around the symbiont pouch. As well as progressive neurotransmitter and endocrine imbalances, including toxic levels of thorocrine production.”

“Bottom line?”

“Ezri’s body is rejecting the symbiont. It’s happening very slowly, but there’s no denying it. And apparently no stopping it either. Her neurotransmitter production has fallen to critical levels, and her body is even rejecting direct isoboramine injections.”

“Isoboramine?” Vaughn said.

“It’s a neurotransmitter unique to Trills. Without a sufficient isoboramine concentration, the neural link between host and symbiont collapses, and the symbiont has to be removed in order to keep it alive.”

“Any clue as to what’s causing it?” Vaughn said, folding his arms.

Bashir shook his head. “All I can tell at this point is what’s probably notcausing it. I can find no trace of any unusual virus or prion anywhere in her body. I tried a course of metraprovoline, lethozine, and metrazene, which will knock certain retroviruses out cold, even if we’d failed to detect them. No response. And I got the same results with the full spectrum of general antirejection drugs, the sort we ordinarily use on organ transplant patients. Neurogenics, for stimulating neurotransmitter production and uptake, have also proved to be a dead end. I even tried bethanamine.”

“Another neurotransmitter?”

“An inhibitor, actually. Bethanamine is a little-known Trill drug set which has been used occasionally to safely separate symbiont from host. But it failed to work on Ezri, for no reason I can fathom. In fact, nothing I’ve tried as yet has made very much difference at all. It’s as though her body is a computer running a program that can’t be altered once it’s started.”

“Could the Sagan’s encounter with the alien artifact have anything to do with this?”

“I still can’t say for certain. All I know for sure is that Ezri’s isoboramine levels are still falling and the critical neuro-umbilical pathways between her and Dax are degrading. Net result: Her body is continuing to reject the symbiont. And I can’t stop it.” Bashir slammed his fist on the desk in frustration and then lapsed into silence.