Shattered: When Winds Blast, the third novel in my contemporary fantasy series, tells the story of the hiding of the grail and its finding side by side.

Deciding to write a grail story took me by surprise. The grail legends were my least favorite part of the Arthurian saga. But when I considered what the theme of the third book of my Celtic trilogy would be, it seemed obvious that the grail needed to be front and centre.

Fortunately, a cup had figured prominently in the first book, so I could not go with the tradition of the grail as chalice. Before I talk about the choice I did make, let me talk about why I said “fortunately.”

In the stories that became best known, the grail is the cup that was used at Jesus’ last meal with his disciples. Additionally, Joseph of Arimathea caught the blood of Jesus that fell from the final spear wound in his side. It was this that gave the cup power. From the late Middle Ages on, it was pictured as made of precious metal and inlaid with gem stones.

The trouble is that Jesus was a relatively poor man from rural Galilee. He would have had a clay pottery cup at his last meal, a Passover celebration. The cup that is pictured in the stories and art resembled the kind of chalice that would be used in a well-endowed cathedral in the late Middle Ages.

This very churchy, very Christian grail is not the earliest representation. In Cretien de Troyes Perceval, the grail is a serving dish which is nourishing a mysterious person hidden from view in the castle of the injured Fisher King.

So, if the grail was not the cup used at the last supper, what was it?

Another possibility that has never held my imagination (and would have been too close to the second book of the series where a trio of heirs of King Arthur play a role) is based on the argument that San-graal, (meaning holy grail) was a mis-understanding of the sang real (meaning real blood), the living heirs of Jesus. It is argued that at Jesus’ death, a woman, likely Mary Magdalene, was pregnant with his child. Therefore, his blood line lives on in hiding.

With those ruled out, what option is left?

I first came across the idea of the grail as a stone in Arthur: The Seeing Stone by Kevin Crossley-Holland, the first of a trilogy. The grail in this story is a vision stone that offers a Twelfth Century boy glimpses back to a Fifth Century Arthur as the two struggle with the path from childhood to their destiny.

Although other stories of the stone as grail make it like the philosopher’s stone, able to change any material into gold, or a cornucopia, able to produce an abundance of whatever is needed, it is the idea of vision stone that caught my imagination.

In my story the stone once belonged to the ancient Celtic goddess Cailleach, but ended up in Merlin’s hands. Through him, it aided Arthur’s fight against the invaders. From him, it is passed to the harper Taliesin who returns to Brittany with Lancelot to defend that knight’s homeland. Because the goddess wants the stone back–as payment for something that happens in the second book of the series–three young Canadians head for France to find it before Cailleach brings a killing winter in August.