Matthew McConaughey and Woody Harrelson – close friends since  their partnership in TV show True Detective – will reunite for a comedy series inspired by a bizarre rumour.

Brothers, sees McConaughey, 56, and Harrelson, 64, playing fictionalised versions of themselves as they investigate the long-running speculation they may actually be siblings.

The rumour that the pair are real-life half-brothers was born after their chemistry on the set of 2014’s True Detective. It gained a degree of legitimacy when they uncovered the unlikely links between pasts of their unconventional parents.

McConaughey’s mother, Ma Mac, had dropped hints in conversation that she had crossed paths with Harrelson’s father, Charles, in Greece while separated from McConaughey’s father, James.

Charles Harrison bears some resemblance to McConaughey. Photo: Houston Police

In 2023, Harrelson confirmed that his father had a brief relationship with McConaughey’s mother, implying he and his fellow actor might be half-brothers.

“We haven’t done a test, but there are too many times that I think to myself, my God, the similarities!” Harrelson told Esquire magazine.

“The things he does, the things he says — just the way he is. I’ve felt that for years.”

McConaughey’s parents divorced and remarried each other multiple times. James McConaughey, who ran an oil pipeline business, died in 1992.

Harrelson’s father Charles was a convicted contract killer who was jailed for life for the 1979 murder of federal judge John H. Wood Jr. He died in Colorado’s US Penitentiary, Administrative Maximum Facility in 2007.

Harrelson has stated he had little contact with his father – who was married four times – during childhood.

McConaughey’s mother married his father three times. Photo: Instagram

While both Harrelson and McConaughey have considered DNA tests, they’ve never gone ahead, preferring instead to lean into the legend of their possible family connection.

McConaughey once noted that he was hesitant because it felt like it could invalidate the father he grew up with, while Harrelson was more open to the idea.

In Brothers, the plot centres on a revelation that threatens to upend Harrelson and McConaughey’s friendship when they uncover a decades-old family secret suggesting they could, in fact, be brothers. 

True Detective was a defining collaboration for the pair. Photo: HBO

According to Apple TV+, the comedy unfolds at McConaughey’s ranch in Austin, Texas, where Harrelson arrives with his family after his daughter’s wedding collapses.

“As Woody turns the ranch upside down in pursuit of the truth, Matthew finds himself juggling an entirely different identity crisis: A potential run for governor of Texas,” the official logline states.

“The result is a heartfelt, chaotic and wildly funny story about friendship, family, fame and the messy line between myth and reality.”

The pair’s partnership in 2014’s True Detective remains one of the most celebrated collaborations in modern television.

Created by producer of the US version of The Office, Lee Eisenberg, the new series premieres on September 23.