It started one cold, misty night beneath Albert Bridge on the banks of the Thames. Church and Ruth came across what at first sight was a mugging: a minor Ministry of Defence official, Maurice Gibbons, was being attacked by a giant of a man. Then the attacker's face appeared to melt. It changed into something monstrous, and Church and Ruth both blacked out at the sight. The incident turned their world on its head, though we all know what the creature was now-one of the unbelievably ancient race of shape-shifters that passed into Celtic myth as the misshapen, demonic Fomorii, things so alien to us our brain can barely give form to the signals it receives whenever we see them. Our mind fakes up the image the best it can, or it simply shuts down and buries the hideous experience in the subconscious, where it gnaws away like a maggot. Church and Ruth were so troubled by this process they were forced to delve into it further, eventually ending up at the studio of Kraicow, an artist who had seen the same kind of thing. He confirmed their worst suspicions.
The shock drove them on the road in search of Laura, whom Church had come across on the Internet and who seemed to have information which might help them; this was after Church glimpsed the ghost of Marianne outside the flat they used to share.
The Fomorii were on their tails immediately. The two of them were saved from certain death by Tom, on the surface a burnt-out hippie. It's hard to believe, but he was actually the mythic figure Thomas the Rhymer, hundreds of years old, gifted with the curse of second sight and The Tongue That Cannot Lie.