'The Show Must Go On: The Queen and Adam Lambert Story' documentary to air on ABC on Monday

LOS ANGELES -- In 2009, American Idol Season 8 runner-up Adam Lambert sang with Queen as one of the final two contestants. Fast forward a decade, and he's performing sold-out shows with the legendary band.

ABC will explore that journey in the TV special documentary, The Show Must Go On: The Queen + Adam Lambert Story on Monday night.

"When we very first met Adam, he appeared to be more, more of a boy, I now see him as an incredibly accomplished man," original Queen member Roger Taylor said of their current lead singer.

This is a big week for Lambert, who appeared on Sunday's American Idol episode as a mentor to the top contestants.

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The documentary comes ahead of the team's already sold-out tour this summer. The two-hour special will feature rare concert footage and interviews with original Queen members and Lambert's parents.

The documentary also explores the death of Freddie Mercury and what followed for the band and for Lambert, then a young boy. Mercury, the group's original lead singer, died of AIDS in 1991.

"In learning more about Freddie over the years and learning that there was definitely a loneliness there, I feel like I have enough in common with some of the things that Freddie was going through," he said.

Mercury's life was the subject of a 2018 biopic Bohemian Rhapsody, which was nominated for Best Picture at the Oscars. Actor Rami Malek, who won an Oscar for portraying Mercury in the film, will also appear in the documentary.

SEE ALSO: Look back at Adam Lambert and Queen's 2019 Oscars performance

The Show Must Go On: The Queen + Adam Lambert Story airs on ABC Monday at 8 p.m. ET | 7 p.m. CT.