In June 1678 two young men fought a duel near Sheerness. One of them was a Navy lieutenant in the garrison there; the other worked in the adjoining royal dockyard. The lieutenant was fatally stabbed; his opponent survived, prospered, and many years later became a Navy Commissioner. He was befriended by a younger colleague who married the dead man's daughter. Nearly fifty years after the duel, the survivor - perhaps as an act of atonement - left his mansion-house to the younger man, whose "best friend" was a Regimental Agent turned Jacobite supporter heavily involved in attempts to overthrow...