Day 15.098: Band in a box

I promised an explanation for why Alt-J appeared to be playing in a box. It was so they could have wrap-around projections like this:

It was staging genius for a band who mostly stood (and sat) still to play their music. At one point the box appeared to fill up with water as they started a song and then they were threatened by a shark that swam around them.

They didn't hide in the box for the whole gig - lifting it out of the way for some of the songs: