Set in the year preceding World War Two, 165 Eaton Place reopens its doors and welcomes viewers back into the enthralling lives of its inhabitants, both upstairs and down. Now a well established and thriving household in the heart of London, life in Eaton Place has moved on; Lady Agnes and Sir Hallam’s family is complete with the addition of two small children and London has settled into an uneasy peace with an apparent aversion to war. With both upstairs and downstairs harboring life-changing secrets and the menace of war creeping even closer, the smooth running of Eaton Place threatens to come crashing to a shattering halt. However, as romance, heartbreak and secrets engulf the household, its inhabitants discover that the real threat is much closer to home.