The Fourth Protocol

Led by Kim Philby, Plan Aurora is a plan that breaches the top-secret Fourth Protocol and turns the fears that shaped it into a living nightmare. A crack Soviet agent, placed under cover in a quiet English country town, begins to assemble a nuclear bomb, whilst an MI5 agent attempts to prevent its detonation.
If the Fourth Protocol is ever breached, there would be no warning, just a nuclear explosion from a bedsitter... The unthinkable has just begun.