Never, ever rule out a John Farnham comeback.

The legendary Australian singer and songwriter was a comeback king throughout his career, turning his back on retirement several times and, at age 38, when many had written him off, delivering the smash album Whispering Jack and its international hit “You’re the Voice.”

Farnham is facing his toughest comeback yet, as he recovers from major surgery to remove a cancerous growth, and a recent health setback. And it’s now that his remarkable career is put under the microscope for a feature-length documentary.

John Farnham: Finding The Voice follows the singer’s life “from the quiet suburbs of Melbourne to ‘60s pop fame, through incredible highs and lows, and ultimately to record-breaking success as ‘Australia’s Voice,’” reads a statement.

Directed by Poppy Stockwell, and featuring commentary from Farnham’s late manager Glenn Wheatley, his late collaborator and friend Olivia Newton-John, international stars Celine Dion, Richard Marx, Robbie Williams and iconic Aussie singers Jimmy Barnes and Daryl Braithwaite, Finding The Voice is the first authorized Farnham biopic.

The 73-year-old artist is one of Australia’s most successful — and most recognizable — recording artists, with hits across five decades.

The greatest of them all is “You’re the Voice,” which led the Australian chart (then the Kent Music Report) and peaked at No. 6 on the Official U.K. Chart. “You’re The Voice” and Men At Work’s “Down Under” are regarded in these parts as the “unofficial” national anthems.

Also released in 1986, its Whispering Jack was the first record to sell over a million copies in Australia, and is now the recognized as highest-selling Australian album in ARIA history, with more than 1.6 million copies shifted.

Farnham has been saluted with awards and honors on many occasions, including the 1987 Australian of the Year, he was made Officer of the Order of Australia in 1996, he’s collected 21 ARIA Awards — the most by a solo artist — and inducted into the ARIA Hall of Fame in 2003.

Last October, Farnham underwent major surgery to remove a cancerous growth. His family last month revealed he’d been hospitalized with a respiratory infection, but was receiving good care.

The feature-length doc is released cinemas on May 18 through Sony Pictures, with a companion soundtrack arriving the following day, May 19, through Wheatley Records / Sony Music Australia.

Watch the trailer below.