When Thomas discovers a strange stone covered with symbols and runes near Hadrian's Wall, he finds himself drawn into the mystery of a secret, ancient organization known as the Stewards. Consulting his fellow academics, the archaeologist is determined to learn more about this elite group and their apparent connection to extraterrestrial visits to Earth over the course of human evolution.

The protagonist slowly unravels a hidden story of Alien influence, from early agricultural developments to modern space exploration, and their partnership with the Stewards to protect and safeguard the knowledge of their visits and to help maintain the balance of the natural order, both on Earth and within the cosmos.

The archaeology professor's research leads him to holy sites throughout Britain and the influence of Celtic Spirituality as he explores what the Celts called "thin" places. Over the course of his quest, Thomas is given another stone etched with a strange glyph, but his journey of discovery puts him in the path of the Apostles of Hades, a sinister group determined to undermine this balance. Drawn to Stonehenge, Thomas meets another professor whose field of study is the ancient stone monument. Revealing herself to be a modern-day Steward, Dr. Vaughn assists Thomas in unravelling the secrets of the artifacts and, together, they gain allies to defeat the Apostles of Hades. When the true power of the stones is discovered, Thomas and the now-powerful Stewards find themselves in a cosmic clash to preserve the future of Earth's existence. The novel is a familiar plot of science-fiction, yet with an intriguing Celtic twist.