A time-traveler who keeps accidentally altering the course of history, and must fix the timeline before it's too late.

Daniel had always been fascinated by the idea of time travel. He'd spent years studying the theories, imagining what it would be like to witness history firsthand. And then, one day, he found himself living the dream - or nightmare, as it turned out.

It started when he stumbled upon an old watch at a thrift store. It looked like an ordinary watch, but when he put it on, he felt a strange sensation - like he was being pulled in a thousand different directions at once. And then, just like that, he was somewhere else.

At first, he thought it was all a dream. He found himself standing in the middle of a bustling medieval marketplace, surrounded by people dressed in rough-spun tunics and breeches. But when he tried to leave, he realized that something was wrong. The streets were lined with stalls selling goods that didn't exist yet, and the people were speaking a language that he couldn't understand.

It didn't take long for him to realize that he'd somehow traveled back in time. But what he didn't realize was that he'd also altered the course of history.

It was only when he returned to the present that he realized what had happened. The world he'd left behind was gone, replaced by one that was darker, more dangerous. He'd inadvertently changed something - he didn't know what - and the ripple effect had been catastrophic.

For a while, he tried to ignore it, to go back to his old life. But he couldn't shake the feeling that he had a responsibility to fix what he'd done. And so he kept traveling, searching for a way to make things right.

But the more he traveled, the harder it became. Every time he changed something, it seemed to make things worse. He'd try to prevent a war, only to trigger a different one. He'd save a life, only to create a new danger.

And then he met her. Her name was Katherine, and she was a historian who specialized in ancient civilizations. When he first saw her, he was struck by her beauty and her intelligence. But what he didn't know was that she would become his greatest ally - and his greatest challenge.

At first, Katherine was skeptical of Daniel's claims. But when she saw the evidence for herself, she was forced to believe. Together, they started piecing together the puzzle of what had gone wrong, tracking down the threads of causality that had led to the disaster they were living in.

It wasn't easy. They traveled from the depths of the Amazon rainforest to the heights of the Himalayan mountains, always chasing the elusive answer to their problem. Along the way, they encountered a host of characters - some friendly, some hostile - who challenged them at every turn.

But through it all, Daniel and Katherine persisted. They worked tirelessly to fix the timeline, always knowing that they might be making things worse. And when they finally succeeded, it was a moment of pure elation - tempered by the knowledge that they might never be able to return to the world they'd left behind.

In the end, Daniel and Katherine parted ways. They'd grown close during their travels, but they both knew that their paths were diverging. Daniel had a new mission now - to keep traveling, to keep fixing the timeline, no matter the cost. And Katherine had her own work to do, cataloguing the events of the past so that they might be better understood in the future.

As he set off on his next adventure, Daniel felt a sense of purpose that he'd never known before. He knew that he might never be able to return home, but he also knew that he was making a difference in the world. And that was enough.