Totality by Kim Harrison

After a solar eclipse opens a way between our world and a paranormal realm, and the dark side of first contact emerges, one woman’s loyalties will be tested in this gripping serialized adventure from the #1 New York Times bestselling author of the Hollows series.

Dr. Renee Caisson never expected that her scientific expertise would lead to a role playing interpreter between humans and the demonic-looking Neighbors. When the door between their worlds opened, she was drafted by the government to study the otherworldly beings and was able to prove her theory: the Neighbors had been to Earth before—and now they simply wanted to save their dying planet.
At least, that’s the story, and everyone—both human and Neighbor—is sticking to it. The Neighbor in charge of the new portal’s operation, Noel, isn’t that sure anymore. Having succeeded in finding a new planet to inhabit, the leaders of her world have made the dark truth of their existence clear to her: the Neighbors forcibly tried to make a foothold on Earth in the past—and they can’t afford to fail again.

But the Neighbors’ ability to magically teleport from place to place has convinced Major Jackson that the only way to keep control of the situation is to embrace it and tell the world of the Neighbors’ existence.

Unfortunately, not everyone agrees.