"That was not bad for your first assignment, Mr. Chekov, but you made a mistake." Supervisor 194 said softly as the younger man sat across from him in one of the burnt orange-colored chairs facing his large ebony office desk with the blinking green sensor cube in his apartment on twentieth century Earth. "Now Kahn will seriously injure you years later at your next encounter with him. You shouldn't have used your name." The man who called himself Gary Seven paused in thought. "I also made a mistake. I should have issued you a code number. However, you should have just pressed the transponder button on your communicator."
"How was I to know about that? I was not totally briefed on its use."
"It is a modified standard issue Starfleet communicator, Pavel." Supervisor 194 paused in thought again. "If I send you back to that moment in time, do you think you could conclude your mission without panicking?"
"You could do that?" Pavel asked in astonishment.
"I could. This time, do not speak. Just press the button."
"What if I encounter my past self? Wouldn't my re-appearance on the Enterprise create a paradox?"
"I hadn't considered that. What if I brought you to another part of the ship so you could help Isis plant a booby trap for Kahn?"
The young Russian smiled.
"A booby trap?"
The supervisor returned his smile.
"Yes. It will be a small bomb, implanted in an odean junction in engineering. By now, the crew should be deploying the knockout gas. I have instructed Isis to drag Miss Mears back into the corridor, making her later believe that seeing Nurse Chapel in Riley's quarters was just a dream. That way, when the real nurse Chapel is back on duty, it will not appear that she was in two places at once."
"That is brilliant! If the bomb kills Kahn, he will not hurt me in the future. However, there is a possibility that the bomb might hurt or kill someone else."
"I wouldn't worry about that. The bomb will defuse itself over time if Kahn is not killed."
"I hope so. So how are we going to plant the bomb?"
"Isis will be disguising herself as Lt. Masters. Since the Negro lady is the assistant chief engineer, no one will become suspicious. Also, since the real Masters will be trapped on the Copernicus, there will be little chance that Isis will be seen disguised as her. However, there will be little time. You two will have to work quickly."
"Very well." Pavel said, pulling himself up from the chair. "I am ready."
Seven pressed a button on his servo and opened the door to his transporter, disguised to look like a walk-in safe.
"Step into the 'safe' and good luck." He watched as the young man disappeared in the blue transporter fog.
When Mears regained consciousness, she was a little surprised but relieved to see Nurse Chapel bending over her, scanning her with a tricorder. As she tried to sit up, the room started to spin. She settled back down on the bed she was on. When she tried to ask where she was, it hurt.
"Don't try to speak, Yeoman. Your larynx is injured. Sorry, I don't have pain medication with me. You will have to wait until I can get you to sickbay." Isis could read the question in her mind. "You are in Riley's old quarters. Two crewmen phasered your attacker and I dragged you in here. It might be a while until the crew retakes the ship."
Mears frowned, wondering how Chapel knew what she was going to ask. Isis looked at her with some compassion, deciding to pretend that she couldn't read her mind. Suddenly, she heard the sound of knockout gas being released from the air vents. Being an alien, she was immune to its effects. Mears gasped and quickly lost consciousness from the effects of the gas. Isis smiled as she morphed into the guise of the black lady engineer and dragged the yeoman back out into the corridor. She gently touched her forehead.
"You dreamed seeing me in Riley's quarters." She said softly. She then quickly made it to the engineering section, fully confident that Mears would be all right, and after learning that the new Russian recruit would be waiting for her. Seven had given him the bomb, and in the short interlude when the crew who were not hiding in the shuttles were knocked out, he gave it to her and she implanted it. Chekov carefully stayed out of sight of the surveillance cameras. Their missions accomplished, both Chekov and Isis quickly beamed off the Enterprise and back to the safety of Seven's apartment.
Unknown to them both, the explosive device would not be discovered by Kahn. Months later, it was going to malfunction, giving Scotty a severe concussion when it went off.* When the surveillance video in engineering was reviewed to determine who planted the bomb, Masters was, at first, unjustly accused of the crime. She was, of course, acquitted when several witnesses testified that she had been trapped on the Copernicus with them and could not have planted the bomb. Also, she had nothing against Scotty, so had no motive for harming him. Spock also verified that during the time it was implanted, Masters was indeed ensconced on the shuttle craft, noting the time index on the recording. It was never determined who the Masters double was. However, some crew members who did not know all the facts were suspicious of her from then on, creating a rather hostile work environment for her. She transferred to another ship soon after that.
* This is the concussion that Scotty would suffer in the original episode "Wolf in the Fold".