CIA officer Carrie Mathison is one of the best in her field, a case officer whose work centers on covert operations meant to protect the United States from terrorist threats. Living with bipolar disorder makes her volatile and unpredictable, but she continues to take extreme risks in the line of duty. With the support of her longtime mentor Saul Berenson, Carrie pushes herself to the edge, even when the cost is her own well-being and sanity.