InthefifthseasonoftheBritishespionagethriller,HarryPearceandAdamCarterbegintosuspectthatmembersoftheBritishestablishmentarecreatingacrisisinordertobringaboutachangeofgovernment.IntheopeningepisodesJulietShawencountersacarbomb,andherlifeischangedforever.PluswemeetformerMI-5,turnedMI-6officerRosMyers(HermioneNorris),whodiscoversashockingfamilyconnectiontotheseason'sgame-changingconspiracy.