Off “Old King’s Highway” on Cape Cod, looking like a cross between a cow barn and a Congregational Church, sits the Cape Cinema. On a hot summer night, underneath Kent Rockwell’s art deco swirl of heavenly bodies (once the largest mural in the world) and in front of the movie screen that premiered The Wizard of Oz in 1939, the Artists Den cast the cinema in a new light with a performance by indie-pop darling Ingrid Michaelson.