Britain has been plunged into crisis by a series of sinister terror strikes and chronic fuel shortages. MI5 supremo Harry Pearce (Peter Firth) and team leader Adam Carter (Rupert Penry-Jones) begin to suspect that the country is under attack by rogue members of the British “Establishment” trying to bring about a radical change in government. The growing crisis necessitates the team working closely with head-strong, ambitious MI6 officer Ros Myers (Hermione Norris - Cold Feet), who makes her presence felt on The Grid, instantly generating sparks with Adam.