As spies go, Carrie Mathison (Claire Danes) is an unusual case.

For a while, she could be viewed as a female antidote to Jack Bauer in 24. He was all action and implausible durability, running against the clock.

Carrie was smart and flawed, a female spy whose strength was the fact that she cared. This was also her weakness. It was a girl thing.

It’s easy to forget, but when Homeland started, there was a male star, Damian Lewis’s Nicholas Brody, an American hero who might gone over to the other side. Mathison and Brody were a thing. They played each other, like lovers do. The thing now, in this eighth and final season of the bipolar agent drama, is that Carrie has become Brody.

She is an American hero, but she’s damaged. Not just shopworn, screwed up to the extent that normality, for her, is an altered state.

Carrie used to fret about being a bad mother. That’s gone. The child is out of her life, only to resurface in moments of calamity which Carrie has caused in the service of her country. In Afghanistan, she meets a widowed woman whose husband was killed because he spoke to the CIA. To Carrie. There: that’s the pain Carrie feels.

But, like a group of American soldiers advancing into an Afghan ambush, we’re getting ahead of ourselves. Carrie needs to be grounded in an observable unreality, preferably one which evinces the chaos of American foreign policy after 9/11. This requires the show’s second questionable hero, Saul Berenson (Mandy Patinkin) to be in a position of influence.

It requires a crisis of such magnitude that it can only be solved by Saul emitting the bat-signal and freeing Carrie from whatever hole she finds herself in. It requires Saul to put his trust in Carrie against all advice, including his own, because a damaged, dedicated woman is better than a box-ticking man, and Saul loves Carrie like a daughter, and sometimes — in moments of terrible weakness — something more.

Previously, on Homeland… Actually, let’s not bother. There isn’t time.

The Taliban are in Washington, threatening to walk out of peace talks because the Afghan vice president has gone off on one, and it falls to Saul to save the day, and maybe the world, and to do this he needs Carrie, even though she is recovering from 213 days in a Russian jail (including 30 days of Off Her Meds torture), and her American polygraph test is all over the shop, indicating deception, if not florid psychosis, to which Carrie replies: “I edit my answers because I don’t trust my own brain.”

Medically speaking, it’s probably inadvisable to treat bipolarity as a superpower. But that’s where we are.

There’s also another woman, Jenna (Andrea Deck) who is being patronised by her male superiors. Carrie treats her with a bracing lack of empathy. “You’re in a hard place trying to do hard things,” she says. “Don’t whine and don’t take no for an answer.” And off she goes, an unstable hero in an unreal world.