With the UK terror threat level raised to severe, Home Secretary Montague holds secret meetings with the Director General of the Security Service, side-stepping her own Minister for Counter Terrorism and the Police. Specialist Protection Officer Budd is on high alert as Secretary Montague's hard-line stance on national security propels her further into the public eye. With his home life becoming more difficult, it appears as if Budd's natural animosity towards the Home Secretary is beginning to fade.
David's theories about a conspiracy at the heart of government look increasingly plausible. But concerns about David's psychological health are raised, and allegations about his and Julia's professional conduct come to light.
Principal Protection Officer David Budd (Richard Madden) has made a major breakthrough in the investigation into the attack on the Home Secretary, but his enquiries have put him in mortal danger. With the clock ticking and no-one left who believes him, David attempts to prove his innocence. But the evidence against him begins to stack up.