Shattered Time

Daniel and Lea have developed the ability to travel in time. Unsure what do to with their new ability, they decide to alter the past to make the world a better place... and make a profit along the way.
Doing so, they inadvertently change the course of human history. Now, people who never should have existed are extremely powerful, and the effects of four global wars have contaminated the planet.
What Daniel and Lea don't know is that four time travelers from the future have been genetically modified and sent back in time, in order to prevent the reckless changes they've done to the timeline.
But in their new, altered reality, one powerful nation exists, and its leaders are prepared to protect their interests - no matter the cost.