England, 1618.

At his manor of Thirldon, ex-Justice Belstrang - still at loggerheads with his old rival Justice Standish—receives devastating news: King James intends to purchase the estate for his favourite, the Marquis of Buckingham—and Belstrang must comply.

In the ensuing turmoil, while his son-in-law George petitions the King on his behalf, Belstrang receives a plea from a dying friend, Sir Richard Mountford, to visit him at Foxhill Manor. To take his mind off his troubles Belstrang goes—and discovers things are not so simple.

Sir Richard is not dying, but desperate. His brother John has been killed in an explosion at the family's iron foundry, down in the remote Forest of Dean. They cast cannons for the Royal Armouries: a privileged and lucrative business. But Sir Richard does not believe John's death was an accident.

Meanwhile, Mountford's cold-hearted son Francis treats him as an invalid. He fears things are being kept from him—and implores Belstrang to investigate.

The mystery deepens when a forester who was seen talking to Belstrang is murdered.

Only after a violent confrontation on the bleak salt-marshes does the truth begin to unfold—and its implications reach far beyond England's shores.

This time Belstrang must follow the trail to a very bitter end, which could be the making of him—or cause his undoing.