A dangerous threat from the past is descending upon the present, in the form of a bio-engineered plague. Mysterious massacres take place in Ghana and the Vatican, both linked by a strange, pagan cross. And when Sigma Force, still recuperating from recent tragic events, is contacted by an old ally (and flame) of one of its chief operatives, the organization is brought into a thickening and deadly mystery.

The race to unlock the truth is complicated at all points by their enemies in The Guild, along with a mysterious assassin who could be working for both sides. Bad history, secrets and lies make it hard to know who to trust, and as the team scrambles to find allies and evade their enemies, the questions continue to pile upon one another. Sigma Force must travel from Rome to Norway’s so-called Doomsday Vault, with a notable stopover on Bardsey Island, to unlock the secrets of old Saints and new biogenetics, and find the Doomsday Key that will save the world.

With The Doomsday Key, James Rollins delivers another slam-bang thriller that deftly skirts the edges of fact and fiction, and leaves the reader wanting another Sigma book in their hands. And while this novel could be read on its own, without having cracked open the other books in the series, I’d highly recommend reading them all. Fans of Steve Berry, Dan Brown, Clive Cussler and James Twining will find a lot to like in the Sigma books, as well as Rollins’ individual adventures.

The Doomsday Key drops June 23rd.

- Reviewed by Jim Tremlett, Eastwood