During an excavation of medieval soldiers from the Crusades, archaeologist Gillian Magwilde and her team find themselves in mortal danger as their discoveries lead them to search for the True Cross. Meanwhile fanatical right wing Christian, Edward Laygass, stands in their way, buying the land where the excavation is taking place and declaring it Holy Ground.
The team of archeologists uncovers bones that they think belonged to slaves from the 18th century. But soon, they realize the bones are connected with the crew of a ship.
The team discovers secret chambers under the city of Bath. Those are dated to Celtic times and tell the love story of a queen and a Roman soldier.
Gillian's ex-lover and archeologist from Iraq comes to Bath to repossess some Iraqi relics which were stolen.
In France, a British World War One tank is found. Some remains are inside. A feud between the Germans and the British starts.
Professor Gillian Magwilde risks everything to find the greatest sword in history. She starts the same search that already made her mother go mad.