Another day. Another zombie T-Rex to put down. All part of the routine for Arthur Wallace and MI37—the government department devoted to defending Britain from threats magical, supernatural, extraterrestrial, and generally odd. Except a zombie T-Rex is only the first of the problems about to trample, slavering and roaring, through Arthur's life. Before he can say, “But didn't I save the world yesterday?” a new co-director at MI37 is threatening his job, middle-aged Russian cyborg wizards are threatening his life, and his coworkers are threatening his sanity.

As Arthur struggles to unravel a plot to re-enact the Chernobyl disaster in England's capital, he must not only battle foreign occult science but also struggle to keep the trust of his team. Events spiral out of control, friendships fray, and loyalties are tested to their breaking point.