Terry travels the road from the English border to Aberystwyth and begins to suspect there is more to Ogilby's atlas than meets the eye.

On the way to St David's, Terry discovers that this was never a road at all. The mystery deepens as dark forces behind the making of the map are revealed.

Following an ancient pilgrim route, Terry discovers that the map contains a dangerous secret, with a trail of intrigue leading all the way back to the throne of England and King Charles II.

The final leg of Terry's journey is the most hazardous of all. Terry becomes the first person to follow this route successfully for 180 years. At the end of his journey, he finally uncovers the deadly political plot which was the real purpose of the map.