Another good book from Alton Gansky. Vanished is an older one, and the first J.D. Stanton book that I've read by Gansky. It's the second in the Stanton series, but stands fine on it's own.
Gansky writes "Christian" novels. That is, one or more of his characters are believers. He does not write the standard Christian novel where a normal person has to deal with something and ends up doing it by relying on prayer or faith, or where a normal person comes to Christ through the events of the novel.
Those things may happen in his stories, but there is much more to them. They read like a Cussler novel, or less convoluted Clancy novel, just with Christians as characters. There's action, violence, blood, bad guys, and plenty of non-Christians.
My favorite part of Gansky's writing though? At least in some of his novels, he goes way deeper, or farther out onto the fringe, of Christian thinking than your "normal" Christian novel does.
Crisis of faith? Sure, in many Christian novels. Characters praying or quoting the Bible? Sure, in most Christian novels. Explanations of higher dimensions, disappearing people, what exactly Sheol and Tartarus might be, strange lights in the sky, possession, fallen angels appearing as extraterrestrials? You won't see many mainstream Christian novels doing that.
Gansky goes there. And he does it well. (Some of those things are from some of his other novels, not necessarily Vanished.)
Vanished has Navy Captain J.D. Stanton investigating the disappearance of the entire population of a city surrounding a secret military research facility. The president's advisor advocates killing everyone on Stanton's team before the secret of the research becomes public, and sends in a black-ops team with intel convincing them that Stanton and his team are in reality terrorists.
Stanton's investigations of the missing people take him underground into the secret lab where he finds an open portal into other dimensions.
As the black-ops team closes in on him, Stanton needs to find a way to escape the underground cavern and survive the battle.