“Mystery Jack” is a short but dark song about loneliness and death, with a distinctive fuzzy guitar riff and various percussion parts (notably sleigh bells). It also features a unique mix with instruments panned hard left and right. The liner notes state that the left channel was mixed by Jarrad Brown of the band Dorsal Fins, making it his only mixing credit on the album (though he does receive production/recording credits).
The song was released on Float Along — Fill Your Lungs on September 27th, 2013.
At live shows “Mystery Jack” has been elusive, appearing after four to five year breaks for a handful of performances before disappearing again. The first known performance was on 2013-04-20 at The Governor Hindmarsh Hotel in Adelaide. Based on available data, the song wasn’t played again until August for full performances of Float Along — Fill Your Lungs, starting with 2013-08-21 at the Bar Open in Naarm (Melbourne). After this run the song seemed to fall off of setlists entirely before appearing five years later on 2018-06-21 at Republic NOLA in New Orleans. The song was played a few more times in 2018, with a performance from 2018-10-09 appearing in the video KING GIZZ vs KEMONITO. After a few more years of silence, the song returned on 2022-03-07, starting yet another period of appearances before falling out of rotation after a Cavs-less, semi-acoustic performance on 2022-05-31. Two years later “Mystery Jack” was played twice, exclusively on the first leg of their US tour. While the initial return on 2024-09-03 saw a fully electric version, the 2024-09-09 performance was semi-acoustic.