Beirut, 2006. CIA operations officer Carrie Mathison barely escapes an ambush while attempting a clandestine meeting with a new contact, code-name Nightingale. Suspicious that security has been compromised, she challenges the station chief in a heated confrontation that gets her booted back to Langley. Expert in recognizing and anticipating behavioural patterns - a skill enhanced by the bipolar disorder she keeps secret to protect her career - Carrie is increasingly certain that a terrorist plot has been set in motion.