The call from the Argelian constabulary did not concern Kirk or Sulu. A planet known for its bars, its exotic dancers - of seven genders, its assortment of intoxicants and its safety would motivate overworked Enterprise crew members to their best relaxation efforts, some of which could reasonably be expected to lead to benevolent incarceration. Argelian jails rivaled some of the best hostelries on other planets. Kirk had his most diplomatic and least intimidating security personnel standing by on the planet to assist with over-zealous revelers.
When the call came in reporting that Lieutenant Commander Montgomery Scott had been charged with the murder of a much beloved singer and dancer, Kirk bolted from the command chair to the transporter room to meet with the planetary authorities.
As Scotty told it, he and McCoy were enjoying a particularly seductive Argelian courting dance performed by Kara, a dancer famed on Argelius II despite her youth. After sitting through many performances and consuming many cocktails it became obvious that Kara preferred Mr. Scott's company to that of the Enterprise's surly doctor. Paying up on his bet, Bones grudgingly congratulated Scotty and left with Keenser to find greener pastures.
On their way to the transport point back to the Enterprise, Keenser and Bones heard the terrified scream from an unidentified woman - clearly in trouble - followed by the yell of a man shocked and dismayed at his situation. Running at top speed, Bones then Keenser arrived to find Kara, bleeding and dying with her eyes open, in the arms of a disoriented and shocked Montgomery Scott.
The Argelians produced a tiny number of Class 5 empaths in each generation. Key to the Argelian public safety and justice system, these empathic "Peace Keepers" sensed the truly dangerous and the truly dumb before any permanent harm befell the Argelian community. All legal proceedings experienced by Mr. Scott from here on would require the presence of a Peace Keeper.
Kirk listened as Prefect Jarvis described what was known and what was suspected. Kirk sequestered McCoy, badgering him about what he'd heard and seen. After a full med scan, Bones confirmed what Scotty pleaded to any who would listen: despite holding the victim and the murder weapon in his hands, he had no memory of Kara's murder.
Jarvis assigned his own wife - Sybo - as the Argelian Peace Keeper. Fairness drove Kirk to insist on two concessions from the Argelians: first, Kirk asked that the depositions and any subsequent investigation be held on the Enterprise and last, Kirk asked that Uhura - an empathic telepath - participate as a Peace Keeper for the Federation. Jarvis agreed over the objections of his chief prosecutor, Hengist - a rather odious and officious leprechaun of a man. As Chief of Protocol, Uhura had diplomatic immunity on Argelius II - a quiet fact Kirk could use if trouble arose.
Sybo and Uhura were on the bridge when the Enterprise suffered a complete power blackout and McCoy's med tech, Lieutenant Kareen Tra-cii was found dead and bleeding in Mr. Scott's arms, the knife alleged to have killed Kara plunged to its hilt in the young Lieutenant's back.
Mindful of the outcomes on Miri's World and Sahndara, Kirk ordered Uhura to stand down and return to her Comm Chief duties. A terse, heated discussion followed but Uhura acknowledged Kirk's order and took over for Hannity. The depositions and investigation moved to the captain's ready room.
After depositions from Kara's father, Tark, and her ersatz fiancé, Morla, Kirk ordered the room sealed and Sybo began her empathic "truth finding" activities. In moments her words confused and alarmed everyone in the room plus one bridge offer whose psionic capabilities sensed a lurking danger trapped on the Enterprise and desperate to escape.
"Beratis"
Sybo chanted.
"Kesla"
Sybo intoned.
"Redjac"
Some in the room recognized the "Redjac" nickname as Earth's most heinous - and most well-known - serial killer, Jack the Ripper.
Whatever Sybo sensed, it had lived for millenia, it fed on fear and it despised women - preyed on them across the galaxy, moving further from Earth into space with man's outward expansion and exploration.
Streaking from her comm position on the bridge to the ready room door Uhura yelled every code she could think of to no avail. Uhura's telepathy read murder in the mind of someone or something in that room.
On entry, Uhura sadly knew that Sybo joined Kara and Kareen whose final repose was in Commander Scott's arms.
With Sybo's death, Uhura argued with Kirk that Scotty's only hope of escaping Argelius II's capital crime death penalty lay in her own ability to complete Sybo's identification of the perpetrator: Uhura emphatically confirmed to Kirk that whatever Sybo identified remained onboard, that it didn't want to be discovered and that only she would recognize the entity's mental signature.
With Scotty's life in the balance, Kirk relented.
Stretching herself along the route her empathic radar felt from Sybo, Uhura identified the entity just before it attacked her and made its escape into the Enterprise computers. It's most recent identity - "Beratis" - exposed it; Hengist the Prosecutor hailed from the serial killer Beratis' planet, as did the murder weapon.
The creature took mere moments to enact its misogynist hatred towards Uhura, knifing her in the chaos of subduing Hengist.
This time Kirk, not Scotty, held the victim as McCoy worked feverishly to remove the knife that nearly impaled Uhura's heart. but for her Dim Mak-trained reflexes.
Kirk did not visit her in Sickbay; her comatose body on the med-bed transformed in his mind into her bleeding body, pale and deathlike in his arms. Visiting Uhura brought the nightmares. The nightmares impacted his ability to captain the ship.