The Rule of Threes

The fifth book in the critically acclaimed DCI Castle series. A protected witness who’s been given a new identity has gone missing. The original case involved William Redman and his South Manchester organised crime group. DCI Castle travels to a remote part of Scotland to make enquiries, and makes an arrest, but discovers he is also being targeted. Are the two things connected?Is Redman involved?Rick is pushed to his limit, but is it enough?