Dr. Jennifer Senka secretly met with her university colleague and long-time friend, Dr. Randal Meyers, in a basement laboratory.

"Look, Jen, I'm going to show you this, but you must keep it to yourself. It'll change the world. Don't be alarmed. Please wait here five minutes."

Randal opened a large chamber, stepped inside, closed it, and vanished. He then reappeared five minutes later.

"So you teleported somewhere and returned?" Jennifer raised an eyebrow.

"No, I time-traveled five minutes into the future. See my watch? It's five minutes behind. I want to visit the past."

"And do what, Randal?"

"Change history for the better."

"To save her?" Jennifer asked quietly.

"Yes." Randal glanced downward. "I invited you because I know you're a world-renowned expert on temporal mechanics."

"I'm curious, Randal, do you think you could build this again from scratch?"

"Of course, I have the plans memorized. Why?"

"You must not have read my entire book." Jennifer frowned. "Especially chapter 14."

"Sorry, Jen, I must admit, I only skimmed it. What does it say?"

"Once anyone time travels into the past, it resets everyones' identity in the present because of the Universe's built-in paradox prevention. So the only best option to preserve one's present self is to stop the time traveler and their invention. I was suspicious of what you've been up to, but I had hoped not ..."

Jennifer pulled out a gun.

Randal stared at her, trembling.