Here's all you need to know about Homeland 4

So, Brody is dead. Long live Carrie. Ten months after former Marine Sergeant Nicholas Brody was publicly hanged in a Tehran square, Homeland fans are rubbing their hands as the ratings-hit show returns to US television this weekend.

So, Brody is dead. Long live Carrie.

Ten months after former Marine Sergeant Nicholas Brody was publicly hanged in a Tehran square, Homeland fans are rubbing their hands as the ratings-hit show returns to US television this weekend.

Launching its fourth season with a double episode Sunday, the award-winning spy show moves the action to Afghanistan where agent Carrie Mathison is building a new life as the CIA's Kabul station chief.

"It gets ugly," said Claire Danes, who as Carrie Mathison has won two of the show's five Golden Globes and two of its eight Primetime Emmy awards. She added that her character is "alarmingly high functioning" in the new season.

When Homeland launched its first series in 2011 -- based on Israeli series Hatufim (Prisoners of War) -- many critics hailed it as ground-breaking, and compelling viewing.

British actor Damian Lewis starred as Sergeant Brody, rescued after eight years of captivity and brainwashing by Al-Qaeda. The viewer is left uncertain whose side he was on as he climbed the political ladder in Washington DC.

Danes played Mathison, a secretly bipolar CIA officer who falls for Brody while investigating him, hiding the affair from her grizzled boss Saul Berenson (Mandy Patinkin). Highlights of the first two seasons included Brody nearly blowing himself up with a suicide vest, killing the US vice president by hacking into his pacemaker, and a bomb attack at CIA headquarters which leaves over 200 dead.

But many critics say the show lost its way in the third season, in which Brody -- spirited off to Caracas after the CIA bombing -- becomes a double agent in Iran but is eventually found out and hanged in the series climax.

The new Jack Bauer?

"It did begin to really sort of meander," said Robert Thompson, professor of popular culture at Syracuse University, who says he's watched every one of the 36 episodes over the last three years. He added: "At this point they've done the kind of innovative, iconoclastic storytelling that they did in those first seasons. Now I think it goes into its Baroque period, I think probably a lot of action would be called for."

Thompson compared it to 24, which was ground-breaking when it was launched only months after September 11, 2001. "Carrie Mathison is the new Jack Bauer would probably not be a completely bad way of going about it," he told AFP, referring to the central character in the the high-adrenaline spy show which ended its ninth season in July.

Teaser trailers for the new season show Mathison -- who has left her and Brody's baby for the Kabul hardship posting -- running drone strikes, one of which goes disastrously wrong killing innocent civilians.

Reviews have mostly been complimentary. Variety TV critic Brian Lowry said the new show "lacks the initial kick the program delivered, but plays like a smart, spare thriller --24 without the James Bond-style super-heroics.

"Homeland might never be a truly great series again, but if it stays on this path it will be an eminently watchable one," he wrote. The Hollywood Reporter's Ken Tucker added: "The necessity of paring things down to essentials has given the show a new, sleeker and sharper sense of purpose."

But an online comment run by the Washington Post sounded a sour note, calling it "the most bigoted show on television." The show had "churned out Islamophobic stereotypes as if its writers were getting paid by the clich?," it said. "The entire structure .. is built on mashing together every manifestation of political Islam, Arabs, Muslims and the whole Middle East into a Frankenstein-monster global terrorist threat that simply doesn't exist," the reviewer said.

The fourth season begins in the US on Sunday before being rolled out in other markets later this month, with Australia screening the show 10 hours after the US premiere, and Britain launching the new season on October 12.