Matthew McConaughey and Woody Harrelson in Brothers Trailer

Matthew McConaughey and Woody Harrelson have offered a first look at their upcoming AppleTV+ comedy series Brothers in a new official trailer.

In the eight-part half-hour series, McConaughey, 56, and Harrelson, 65, play fictitious versions of themselves who discover they might actually be brothers. The storyline plays directly off long-running real-life rumors that the two Hollywood stars share biological parentage.

The newly released teaser begins with Harrelson arriving unannounced at McConaughey's ranch in Austin, Texas, after his daughter's engagement dissolves. Wreaking havoc on the property, Harrelson turns the household upside down while McConaughey toys with a political campaign to run for Governor of Texas.

The plot thickens when McConaughey's onscreen mother, Ma Mac, played by veteran actress Holland Taylor, reveals a longtime family secret suggesting that the two close friends could be brothers.

Determined to uncover the truth, Harrelson presses the matter despite the chaos it causes. The trailer highlights comedic exchanges between the stars, including a moment where Harrelson's onscreen wife, played by Brittany Ishibashi, tells him: "This is all very dramatic." Harrelson quipped in response: "Of course I'm dramatic; I'm a f***ing thespian."

In another zinger from the snippet, McConaughey haughtily describes himself as an Oscar winner before turning to Harrelson and asking what you call it when someone does not win. McConaughey won the Academy Award for Best Actor for his performance in the 2013 drama Dallas Buyers Club, while Harrelson is a three-time Oscar nominee.

Trailer details and cast members

The comedy series features a supporting cast that includes Natalie Martinez, Ella Grace Helton, Noah Carganilla, Oona Yaffe, Nolan Almeida and Highdee Kuan. Actor and Armchair Expert podcast host Dax Shepard also makes a cameo appearance in the trailer.

AppleTV released the preview snippet across social media platforms on Tuesday. Along with the trailer, the streaming platform posted a caption that read: "Based on a “true” rumor. Matthew McConaughey and Woody Harrelson star in the new comedy series, Brothers. Premiering September 23 on Apple TV."

McConaughey and Harrelson also serve as executive producers on the project. The series expands on the real-life friendship between the two Texan actors, who previously starred together in the acclaimed first season of HBO's crime drama True Detective.

Social media teaser and release date

The project comes shortly after McConaughey teasingly fueled public speculation about their relationship last month. Wishing Harrelson a happy birthday on Instagram alongside a throwback photo of the pair, McConaughey wrote in the caption: "From another mother? Happy birthday, brother."

The official AppleTV account playfully commented on McConaughey's birthday post at the time, writing: "Someone get these guys a comedy series."

Reports that the two actors could be biological brothers first surfaced after McConaughey's mother, Mary Kathlene "Kay" McConaughey, made a revealing comment to Harrelson. While gathered with the family, she mentioned that she "knew" Harrelson's father, hinting at a past romantic connection in West Texas, according to Variety.

Origins of the brother rumor

The disclosure prompted McConaughey and Harrelson to look into their respective family timelines. McConaughey was born in Uvalde, Texas, while Harrelson was born in Midland, Texas, two cities separated by roughly 279 miles.

Upon comparing dates, the close friends pieced together that Harrelson's father had been on furlough from prison around the exact time McConaughey's parents were getting their second divorce.

Harrelson's father was Charles Voyde Harrelson, a convicted contract killer who received a life sentence for the 1979 murder of a federal judge. He was also implicated in dozens of other murders during the 1960s and 1970s.

During his childhood, Harrelson had little contact with his father, who abandoned the family when Harrelson was seven years old. As an adult, Harrelson sought to rebuild a relationship with Charles, visiting him in prison until his death in 2007.

Family history and DNA testing

While Harrelson has expressed a desire to take a DNA test to confirm whether they are siblings, McConaughey has been more hesitant to pursue formal testing. McConaughey explained that confirming the rumor would upend his understanding of his own family history and the man who raised him as his father.

Despite the uncertainty surrounding their actual lineage, the intriguing possibility inspired the duo to channel the rumor into their new comedy series. Brothers is set to premiere globally on September 23 on Apple TV+.