A Ring of Truth. The Valiant Chronicles, #2

To ensure her daughter's safety, Carolyn Fairchild has surrendered to the Agency and the aliens who repeatedly abduct her. Determined to sever the aliens' hold on Carolyn and the other abductees, Michael Valiant, Agency assassin, has gone rogue. He's made his way to the Northwest Territories to find the alien base in The Valley of the Headless Men. But time is running out. The aliens have almost completed their experiments, and when they do, the captive abductees will be executed.
While Carolyn chooses between betraying Michael and protecting her daughter, Michael finds himself pursued by a vengeful ex-partner with whom he once almost had an affair. Unaware they are repeating a pattern enacted over many lifetimes, Michael and Carolyn must break the cycle or continue enacting it in lifetimes to come. A Ring of Truth can be read as a stand-alone novel though it continues Michael and Carolyn's story from The Experiencers.