The Grace Dieu Project - Chateau Sarony, #2

The remains of a WW1 soldier and four WW2 soldiers are discovered beneath a deserted farmhouse in France. Not so unusual except for the fact that they all appear to have died at the same time. How this is possible is a question Anna and Martin Price must resolve when asked to help out an old friend. This, the second Chateau Sarony mystery leads the couple on a trail of deception and murder spanning several decades.
How does Martin's old US Marine friend fit into the picture? Is he as helpful as it first appears or is he following an agenda set by other unknown parties...