Lee Jang Woo built a "Glass Castle" on 'Immortal Song'.

On the September 19th 'Actors Special' of the show, Lee Jang Woo covered K2's 1999 track "Glass Castle". The actor blew the audience away with his unexpected vocals for the soft rock ballad.

Despite Lee Jang Woo's impressive cover, it was Lee Tae Sung and Song Yoo Bin who took the final win this episode.

Watch Lee Jang Woo's performance above and the original below!