My sci-fi story:

My story takes place in the late 2050s. A group of scientists, funded by private government agencies, have managed to figure out time travel. They decide to send secret agents and a group of doctors back through time to try to eradicate specific diseases. They feel that they’re doing a successful job and have managed to fly under the radar of the general public for about 10 years. Until someone visits the “time travel facility” from decades in the future and explains what has happened because of them meddling with time. 

The key ideas of my story are time travel and genetic mutation. Like most stories about genetic mutation/engineering, while the majority of the characters believe they are doing a good thing for the world, they later learn that every action has repercussions.