SINGAPORE - The final trailer for Mr Unbelievable - starring actor Chen Tianwen as the titular character - has been released ahead of the local film's opening on Dec 3.

At just under two minutes long, the YouTube clip provides a glimpse into the life of wannabe singer Eric Kwek (played by Chen) as he attempts to achieve fame and revive Singapore's getai industry.

Mr Unbelievable, helmed by director Ong Kuo Sin, also features veteran actors Liu Lingling and Marcus Chin, as well as rapper and Ah Boys To Men star Tosh Zhang.

The comedy is a spin-off from the Channel 5 dramedy Spouse For House, which was the inspiration for the hit zany music video Unbelievable.

Unbelievable, launched in April, became an unexpected hit when it went viral, earning a mention on the online site of Time magazine, which described it as an "instant mood lifter".

The 52-year-old Chen dons a '70s getup and ridiculous-looking wig. He spouts cheesy lines such as "You blossom like a flower, I so stunned like vegetable" and "Please be the metal cable to my cable car".

He became the centre of attention almost overnight. In August, Chen scored a getai gig and earned a four-figure sum by singing two songs, including Unbelievable.

A month later, he was a special guest at local singer-songwriter JJ Lin's concert at the Singapore Indoor Stadium.