L'Affaire Louis' Trio (L'ALT for short) were an art pop band from Lyon, France. The band formed in 1982, and in 1986 were signed to Barclay records, France, who released their first album, 'Chic Planète'. The members were: singer / bassist Cleet Boris (aka Hubert Mounier), guitarist Karl Niagara (aka Vincent Mounier, Hubert's younger brother) and keyboardist / drummer Bronco Junior (aka François Lebleu, who died in December 2008). In 1987, L'Affaire Louis' Trio were awarded the prize for best newcomers at France's prestigious 'Victoires de la Musique' ceremony.

The trio stayed together until 1997, when Vincent Mounier left during the recording of their 1997 release, 'Europium'. Since then, the band was dissolved, but Hubert Mounier recorded with drummer Lebleu on his first two solo releases, 'Le Grand Huit' (2001) and 'Voyager Léger' (2005). He has also worked extensively as a comic book artist under his Cleet Boris pseudonym.