It’s autumn, 1987, and as a major arms control summit looms, Elizabeth is pushed to her limits as never before. Philip, meanwhile, has settled into running the newly expanded travel agency – until an unexpected visitor makes a disquieting request.

In the aftermath of a disastrous operation, Philip and Elizabeth clash about how to handle things with Paige. Stan struggles to contain the growing risks of Sofia and Gennadi's fraying relationship.

After picking up a distressing piece of intelligence, Elizabeth takes extreme measures to get close to a Soviet negotiator. Philip shares some stunning news with Henry.

With the arms control summit under way, a shocking revelation from Philip throws Elizabeth - and her work - into turmoil. Stan follows a dangerous hunch.

Elizabeth wrestles with competing loyalties, and Philip has an encounter that turns into much more than he had bargained for.