"Commander, in my office, please," Picard announced as he stepped onto the bridge and towards his ready room.
"Aye, sir. You have the bridge, Data." Tasha stepped into the room ahead of her captain, as he stood aside to let her through the door first.
"Have a seat, Commander Yar," Picard said, taking his own chair behind his desk. He sat ramrod straight, his hands resting palms down on the table, his attention completely on his first officer.
"Why have we left the system without my order?" He said without preamble.
Tasha mentally reached to understand the purpose of his question. She couldn't ever remember the Captain being angry at her taking the initiative and delivering orders, so he must have some other reason in mind. "To minimize the unexplained delay, captain. The detour from Pacifica hasn't been recorded on the ship's logs, so we wanted to arrive there as close to the scheduled time as possible."
"Ah. No unauthorized transmissions reporting our position?"
"None that we detected sir."
"How did the crew feel about the sudden change in orders?"
Tasha frowned. "They trust you, sir. Implicitly."
"Good, good," Picard nodded. "I will have to call upon that trust before this matter is completed, Commander."
"Are you able to explain more yet, sir?" Yar asked hopefully.
"Not yet, but very soon. Commander, we need to divert course to Sector 001."
"Earth, sir? Why?"
"I cannot say. But there's no need for radio silence, this time. I will send a message to the Pacificans apologizing for our unavoidable delay." He tapped on his desk viewer. "You will order the course change?"
Tasha stood. "Right away, captain."
"One more matter first." He waited until Yar resumed her seat.
"Commander, I rely on you to be my eyes and ears with the crew. To assess their allegiance. Their loyalty." He continued to meet her eyes, unblinkingly.
Yar's stomach turned to ice. "They're Federation officers, sir. Their allegiance is not in question."
The captain nodded stiffly. "Of course. All loyal officers here. But… what about the android?"
Tasha now strongly suspected that she wasn't talking to Captain Picard. She chose her words carefully. "Lieutenant Commander Data is a machine, sir. He knows to follow your orders."
"Excellent! Excellent. Dismissed, Commander."
Returning to the deck, Tasha gave their new orders. "Geordi, set a course for Earth."
"Earth, sir?" La Forge confirmed.
"Sector 001, government of the Federation, Starfleet Headquarters," she confirmed. "How long until we arrive?"
"At our present speed, about eighteen hours," Geordi estimated.
"How about at Warp 3?"
The question provoked a look of surprise from the bridge crew, but the navigator answered, "A little over four days, sir."
With a solemn nod, Yar issued the orders. "Engage on a course to Earth. Warp 3. Data, please take the bridge. I'll be in Security if you need me."
*****
"Thank you for your time, Worf. Much of this is just a verification of the medical records, but we want to make sure that we have sufficient detail for emergency surgery."
"Of course."
The doctor waved her sensor up and down the officer's back. "A redundant brain stem. The ventral stem is the one connected to your peripheral nervous system for body control, correct?"
"I… do not know. I was led to believe that Klingon organs tend to share functions so as to compensate better if one is damaged."
"Who told you that?"
"You, doctor."
Crusher nodded. "There's no obvious entry point. Bony plates project from the fused palate within the skull; you have redundant casings from the rear cranial occlusions all the way past the lumbar cage. Worf," she asked with frustration, "if a Klingon needs brain surgery, how do they even get in there?"
"My study of Klingon culture did not include surgical practices, doctor," Worf deadpanned. "Is there anything else I can help you with?"
She gave him an irked look. "Strip to the waist, please. We're going to do a toxin sensitivity series. This won't take long."
*****
"Please, Data - just tell me I'm not crazy."
The android looked from his personal desk console, on which the security footage had just been displayed, to the earnest expression on Tasha Yar's face. "I have seen nothing to indicate that your sanity is in question, Tasha. Your reasoning capabilities appear to be sound, and all of the phenomena that you have identified to me do, in fact, appear on the recordings as you have described."
She sighed in relief. "I just… didn't know who to go to with this. The captain and Soriana."
"Certainly you can come to me with your concerns, Tasha. We are friends, are we not?"
"Close friends, Data. Thank you."
"I would, however, like to propose an alternate explanation for these observations."
Yar's eyes narrowed with skepticism, but she nodded gamely.
"We see the captain and the counsellor return from a meeting taken under conditions of great secrecy," his fingers flew over the inputs to replay the images. "Lieutenant Commander Turhal carries a type-304b shielded equipment case in one hand with minimal shift in her gait, implying a total mass for its contents of under fourteen kilograms."
"If you say so," Yar conceded.
"She brings the case directly to Sickbay and leads Doctor Crusher into the office. They lock the door. Twenty-three seconds later, a phaser discharge is detected in the office. Lietenant Worf opens the door four minutes and thirty-four seconds after that, at which time the counsellor exits Sickbay with the equipment case. She returns to her quarters, and the case is not seen again."
"So the contents of the case are either in Doctor Crusher's office," Tasha picked up the thread, "or Soriana's quarters."
"Unless they were carried out of one of those locations concealed on someone's person, or otherwise removed such as by teleportation."
Yar shook her head. "If the contents could be concealed under clothing, why the equipment case?"
Data nodded toward her. "A valid point. But consider where the counsellor and the doctor were."
"Her office… where she keeps the surgical alteration equipment!" Tasha's faced screwed up incredulously. "You think the contents of the case might have been surgically implanted in Soriana's body?"
"Unlikely in four minutes, but possible. My main point is that there are many possibilities for this data. Based on reviewing this footage, my strongest hypothesis is that Captain Picard and Counsellor Turhal were briefed on a secret mission while on the planet for which Doctor Crusher's assistance was needed. Soriana was given some device needed for the mission."
"That doesn't explain the phaser discharge."
"I suggest that there was no phaser discharge. Instead, there was an energy burst associated with activating the device that the internal sensors recorded as a phaser discharge."
"That's a stretch," Tasha opined.
"It is. But the prior probability is higher than what you are proposing." Data said it with such poise, such apparent calm, that Tasha found herself considering the two scenarios.
"In isolation, I agree," she finally conceded. "But their unusual behavior doesn't fit your explanation. First, the captain talking about loyalty and allegiance like we're on an old Earth sailing ship and he suspects mutiny. And then this." She brought up another file she had compiled in the last four hours. "The captain accessed a bunch of personnel files, navigation logs, and his own captain's logs."
"You believe this to be suspicious behavior?"
"Yes! Especially since Soriana and Beverly both did the same thing. Plus the doctor made seventeen separate queries on basic medical information and procedures."
Data looked through the access logs. "None of this requires clearance for sensitive information. You are correct that it does not fit their regular usage patterns." He scrolled faster. "Intriguing. Have you continued to track their movements?"
"No. Once I reviewed the access logs, I stored everything on my drive an came here. Why?"
"I believe we should review the recordings taken of Transporter Room 3."
*****
The ship's first and second officers walking to Security together was an ordinary event, triggering no more than a nod or word of greeting from the crew they passed. Once there, it was a matter of accessing the recordings for Transporter Room 3.
"There she is," Data announced, freezing briefly on Soriana's entrance to the room, then quickly speeding through her time at the console. "Thirty-eight minutes, five seconds. Rather than merely erase the transporter trace, the counsellor accessed the pattern from when she and the captain had beamed down to the planet." A graphic of the two of them appeared on the console display. "She added an equipment case to the record, but it's shown resting on the ground rather than in her hand as we can see from the security record."
"So they are imposters," Yar lamented.
"That is the most likely explanation, but it is also easily resolved. Permission to apprehend Lieutenant Commander Turhal?"
*****
Treracknu was feeling sorry for himself.
He sat alone in his host's apartment, looking at the nauseating plate of greens and melons front of him. His host was getting hungry; he'd have to choke it down.
Of all the marvelous omnivorous species in this quadrant - humans, Vulcans, Cardassians, Ferengi - he had to be stuck with a Queen-damned Haliian. An obligate herbivore, lacking the enzymes to digest meat. Bad enough that Grionta had confirmed a dearth of live food on board; he couldn't even eat a replicated tube grub or plate of gagh.
As if that wasn't bad enough, he was getting nowhere with his host's empathic abilities. There was something, certainly - a nameless hum, almost, that intensified whenever he was close to another crew member. But without any instinctual way to interpret the sense, getting any meaning from it would take months of experimentation.
Even worse, he was the one stuck running around the ship while Grionta got to play doctor and Bristak stayed out of sight as captain. It was truly unfair how -
The sound and feel of teleportation was increasingly familiar, but Treracknu's new surroundings were not. A bed, chair, and toilet; a force field protecting a closed door; a desk with a small computer console. He went to the latter, and confirmed two things: the new location was a cell in the brig, and Soriana's biometrics didn't unlock any communicationa or records access.
Now, Treracknu really felt sorry for himself.
*****
"A differential between the trace patterns reveals the situation clearly," Data pointed to the graphic. "A parasitic organism attached directly to the brain stem."
"Controlling them directly?" Yar asked.
"Without subjecting them to a detailed medical scan, I cannot say for certain. But it is the most likely explanation given what we know."
"Why didn't the biofiter catch it?"
"Again, I cannot be certain without further scans," Data began, "but the transporter trace analysis systems cataloged the region including the parasite as being Haliian nerve tissue. The mechanism by which the alien interfaces with its host may also include some sort of adaptive mimicry."
"Data, we have to do something," Yar pleaded. "These… things, are doing who-knows-what to their brains. Eating them alive, for all we know."
"I share your concern. Unfortunately, Doctor Crusher is the only person on board with the expertise to both diagnose the exact nature of the neural connection, and successfully remove it without damaging the host."
Yar finished, "And Beverly is one of the infected."
The android nodded. "I would surmise that this is not coincidental. Presuming these parasites have prioritized remaining undetected, Counselor Turhal and Doctor Crusher would be two of the three most logical targets."
Yar thought for a second. "The third would be Geordi? Because he'd see the parasites easily with his visor?"
Data nodded. "Again, this is speculative. But while Lieutenant La Forge might not immediately notice something amiss just from observing a host, there is a high probability that he would detect the alien organism if alerted to do so."
"How easy would it be to run a differential scan of each person on the ship against their last transporter trace?"
Data blinked. "Trivial. For the full complement of nine hundred seventy-three individuals currently on board, not including myself, the scans and analysis will take three minutes, fourteen point five seconds."
"Please do."
*****
As she and Data waited for the turbolift to arrive at the bridge, Tasha thought about how lucky she was that Captain Picard relied on his first officer to receive pertinent information. Many staff officers had automatic alerts for a variety of actions that could occur aboard their ship, but Picard had confided in her months ago that he hated that constant false negatives these would receive. Other than certain emergency alerts that were automatically reported the captain according to Starfleet regulation, the captain had trained her, the chief engineer, and the bridge officer to keep him informed.
With luck, then, Picard was still in the dark about Turhal and Crusher having been made guests of the brig - an action the ship's systems would not allow them to try against the captain… yet.
Geordi La Forge rose from the captain's chair as soon as the first and second officers stepped onto the bridge, but she held up a hand before he could replace the midshipman at helm. "We have a problem," she explained, alternating her facing between Geordi and Worf. "Please trust us. Computer, initiate emergency Command Override, Protocol Seven."
"Protocol Seven, Camus II Protocol," the computer's voice coldly announced. "State imposters."
Yar swallowed; she couldn't allow her voice to waver. "Imposters are Captain Jean-Luc Picard, Counsellor Soriana Turhal, and Doctor Beverly Crusher."
"Three imposters identified. First officer authorization required."
"Commander, what -" Geordi started, the stress obvious on his face.
"I'll explain in a minute," Yar insisted. "Computer, confirm authorization, Yar Ishara Seven Nine Nine Four Alpha Four Eight."
"Confirmed," the computer intoned. "Does the second officer agree?"
"Affirmative," Data said.
"Second officer authorization required."
It was at this moment that Captain Picard walked onto the bridge. There was a momentary tableau as Yar, Worf, and La Forge all froze, staring at the one Tasha was currently locking out. But Data did not hesitate.
"Confirm authorization, Data Epsilon Salar Four Seven Giraffe Nueve Tres Gimmel H Ichi Ichi Ni HuchQeD …"
"Commander, what's going on here?" Picard asked over the increasingly incomprehensible babbling of the android.
"I'm sorry, sir," Tasha replied, drawing her phaser on the man. "You're being temporarily relieved of command."
"... Athos Pudding Vermont," Data finally concluded.
The computer answered, "Confirmed. Command Override Protocol Seven is in effect."
"A mutiny, then," Picard observed calmly. "Very disappointing. Lieutenant," the captain turned to Worf, "please disarm the Commander and take her to the brig. Then we can sort out this override."
"Belay that," Tasha spat. "That's not the captain. Ask him what martial art you do."
Picard raised his voice. "Lieutenant, if you don't act against these mutineers right now, your career is over just as theirs are."
Worf's phaser was out but pointed downward. "I understand, sir. Can you please answer the question? Which martial art do I train and compete in?"
The man frowned. "Lieutenant Worf, you were raised on Gault by Sergey and Helena Rozhenko. I… apologize, for not taking a more active interest in your hobbies, but I assure you I am the captain you know."
"Captain Picard came to watch one of my classes less than a month ago," Worf growled, pointing his phaser at the imposter. "You have his voice, but you clearly lack his memories. Stay where you are."
In an instant, the captain's frown melted into a manic smile. "Very good. Very good, indeed. I must commend you, Commander," he addressed his first officer. "We didn't view you as a threat. Our mistake."
The distance between Picard and Worf was the smallest, and the captain crossed the distance with surprising speed. Two phaser beams set to stun both hit him to no visible effect as he hit the phaser out of Worf's hand and lunged in further to grapple the Klingon.
Worf was having none of it. Although surprised at the captain's raw strength - much higher than he was used to, when sparring with humans - he was no match at all for Worf's training. The human's grasp was easily sidestepped, and a following motion with a grab sent the captain flying past his tactics officer to hit the wall with a reverberating thud.
Picard blinked up from the floor, momentarily stunned, as Data moved quickly to the ops station. "The computer no longer recognizes Captain Picard's command authority. Initiating detention protocol."
Just as the human found his feet, sneering, a chiming sound heralded his departure from the bridge.
"What… was all that about?" Geordi La Forge recovered from his extended gawk at the unexpected altercation.
"Brain slugs," Yar answered simply. "Take the helm, please, and lay in for Starbase 133. Warp 8."
"Yes, sir. But I hope we're getting a briefing soon?"
Yar nodded, "Just soon as we're underway. Engage."