Future's dark past

"The catastrophic Purge War at the end of the twenty-first century destroys planet Earth, jeopardizing the future for the remnants of humanity. Horrific repercussions roll across the ages until, generations later, a scientific group called the Time Forward Project harnesses a deep-space wormhole in which they can travel through time. They find the portal unstable and shrinking, but they have little choice but to take desperate, drastic measures a...