The blood promise - Mark Pryor

Hugo Marston must figure out what lies hidden inside an old sailor's chest before a 200-year-old blood promise is revealed and claims another life.

In post-Revolution Paris, an old man signs a letter in blood, then hides it in a secret compartment in a sailor's chest. A messenger arrives to transport the chest and its hidden contents, but then the plague strikes and an untimely death changes history.

Two hundred years later, Hugo Marston is safeguarding an unpredictable but popular senator who is in Paris negotiating a France/U.S. dispute. The talks, held at a country chateau, collapse when the senator accuses someone of breaking into his room. Theft becomes the least of Hugo's concerns when someone discovers a sailor's chest and the secrets hidden
within, and decides that the power and money they promise are worth killing for.

But when the darkness of history is unleashed, even the most ruthless and cunning are powerless to control it.