Zero Frequency

Two years ago, the tunnels opened. They appeared across the planet in a single night: perfect, silent craters that the Earth had no explanation for. Nothing has come out of them since. No contact, no demands, no war. Humanity dropped a nuclear weapon into one of them, and the mouth swallowed it without a sound. What has come out is the dread. A slow, global unease that curdles into curfews, paranoia and quiet collapse.
Miguel Reyes Brooks stopped caring a long time ago. A once-respected investigative journalist, now living on the last of his benefits and a barman's patience in post-Irruption London, he has made his peace with the end of the world. Then his estranged father, an art dealer who buried the family name chasing conspiracies, is murdered. In his father's safe, Miguel finds notes written in a symbology older than any known language, a hand-carved hexagonal rod, and a map.
Every ley line on that map ends exactly where a Harbinger tunnel opened. His father was not insane. He was early. To finish the work, Miguel will have to trust a neuroengineer nobody at her own institution takes seriously, survive whoever killed Julian Reyes, and accept a conclusion he has spent his career refusing: the oldest monuments on Earth were never monuments at all. Zero Frequency is a hard science fiction thriller about what our ancestors were really building, and what they built it to hold shut.
From the author of The Loop.