The American television network Showtime is becoming synonymous with highly acclaimed drama and post 9/11 series Homeland (2011) is no exception. Barack Obama is reportedly a huge fan of the programme and millions of UK viewers watched the tense series finale on Sunday 6 May. The plot concerns Marine Sergeant Nicholas Brody who has recently returned from Iraq after being missing for 8 years. His wife, children and army colleagues have long assumed that he is dead and Brody must rebuild relationships while being haunted by his time in captivity. Hints that he was tortured and forced to beat his fellow American hostage are referenced by brief flashbacks.

Arguably, however, the real drama stems from his relationship with an obsessed CIA operative, Carrie Mathison. She has been given secret information that an American soldier has been “turned”’ by Al Qaeda and is convinced that Brody is that officer.

Mathison is determined to unravel Brody’s secrets and foil a potential terrorist plot on American soil. The character is single-minded, even at times fixated on Brody and audiences watch as despite all the evidence to the contrary Carrie is convinced he is a “terrorist’ and illegally installs surveillance cameras in his home to watch his every move- even while Brody makes love to his wife.

We know that Carrie’s personal life is chaotic. Male colleagues discuss their brief flings with her and we also see Carrie trawl bars for anonymous sexual liaisons. These scenes are contrasted by those with Carrie’s sister, a doctor who looks after her father and two daughters in a comfortable family home.

However Carrie is more than a typically driven CIA operative with no time to shop, eat or form ‘normal’ relationships. She has bipolar disorder, a fact we discover gradually in scenes that show her secretly taking tablets in her bathroom and later when her sister Maggie, rations her medication.

Meanwhile Carrie orchestrates a number of situations where she can get close to Brody including an apparently random drop in to a veterans support group meeting (episode 4) but when they meet up in a bar they both get increasingly drunk and Carrie has unprotected sex with him in a car in a parking lot.

At this point audiences can be in no doubt that Carrie is in the midst of a manic episode and we see her unravel – a process that is difficult to portray in other media formats such as news or documentary.

The characterisation of Carrie as having bipolar disorder may or may not be “realistic.” Certainly online commentators have highlighted this as an obvious weakness in an otherwise fairly realistic storyline.

How could she have security clearance with a mental disorder? Could an employee seriously conceal their medical history from the CIA?

However, what makes her characterisation interesting is that Carrie’s illness is part of her identity. Indeed, her bipolar disorder possibly enhances her ability to do her job. As many of the characters in the programme remain unaware that Brody is indeed working for Al Qaeda, only Carrie with her intense focus on the smallest detail comes close to piecing the jigsaw together.

It is well documented that media representations of those in mental distress are considered to fuel public prejudice and misconceptions. In some ways this portrayal is stereotypical in emphasising the link between gender, mental illness and “out of control” sexuality.

Without medication Carrie is unable to control her impulsive behaviour and we see the great cost to her personal life and career. At the same time this representation potentially offers us a new take on the mental illness “survivor” where the illness allows the protagonist to perform to a higher level.

At the very least Homeland has brought bipolar disorder into the mainstream media and provided a platform for discussion concerning symptoms, treatment and the ethics of secretly treating relatives.

This review first appeared on the BMJ blog