When does The Diplomat return?

The Diplomat is an American political thriller television series. It stars Keri Russell as a veteran U.S. diplomat who is unexpectedly appointed as the ambassador to the United Kingdom amid an emerging international crisis. The series has received critical acclaim for its writing, pacing, and performances, particularly those of Russell, Sewell and (beginning in season 2) Janney.
The series centers on Kate Wyler, the new U.S. ambassador to the United Kingdom. She helps to defuse an international crisis and forges strategic alliances. She also manages her deteriorating marriage to fellow career diplomat Hal Wyler.