Into the Looking Glass - Ringo, John

Interdimensional gateways open Earth to aliens--invading predators and less hostile alike--but if a way is not found to close those gateways, the less belligerent aliens might annihilate the entire Earth to save their own worlds.

Into the Looking Glass 2007, Baen Books

ISBN-13: 9781416521051

Mass-market paperback

Into the Looking Glass 2005, Baen

ISBN-13: 9780743498807