<br>The bloated remains of a man are discovered bound to a derelict pier in Orkney and newly promoted DCI Lukas Mahler dispatches a team to investigate. But when the body is identified as Alex Fleming - Mahler''s former colleague from his time in the Met - the case becomes personal.<br><br>Mahler''s investigation takes him from his old stamping ground of London to the world of organised crime, and from sixteenth-century witch executions to Fleming''s most notorious unsolved case: the ''Witchfinder'' murders. Are the runic symbols found with Fleming''s body proof the killer''s struck again - or is there an even darker story to be uncovered?<br><br>With pressure mounting from all sides and demons from his own past surfacing, Mahler is faced with the most complex moral decision of his career.