It's May Day 1592 and, after a night of revelry and a day tending the sick, Dr Simon Forman falls into bed utterly exhausted. Soon afterwards, he is woken by a man on his doorstep who is dying from a sword thrust, and next morning Simon is summoned to Whitehall, accused of harbouring enemies of the state.
To prove his innocence, he agrees to journey to Edinburgh on a secret spying mission. But once he enters the Borders between Scotland and England - where the bloodthirsty Reivers vow a ’life for a life’ - he realises that death is stalking him. As one gruesome murder is closely followed by another, Simon must act quickly to identify a ruthless killer before his own life is put in jeopardy . . .