The pair star as a couple whose love takes a sinister turn in the video for 'Filth' by A Band of Buriers.
Shot in rural Gloucestershire, the video was written by Rob Hayes and directed by Blake Claridge.
'Filth' is the title track from the band's upcoming studio album, which is released next Tuesday (July 10).
The band launch the album on Tuesday with a show at RADA's Studio Theatre presented by a special guest.
A Band of Buriers were formed in 2011 and consist of singer James P Honey, cellist Jamie Romain and female backing choir Annie Broadbent, Georgia Maguire and Anna Byers.
Lewis's Harry Potter castmate Daniel Radcliffe recently starred in the 'Beginners' music video by Slow Club.
Fellow Hogwarts alumnus Emma Watson previously appeared in the promo for One Night Only's 'Say You Don't Want It', while Rupert Grint featured in the clip for Ed Sheeran's 'Lego House'.