Having conquered the UK's hearts, minds, and muddy fields with their first three albums, the Hartnoll brothers used In Sides to push the limits of rave. "The Girl With the Sun In Her Head" is an easygoing anthem that dances like sunbeams. "Petrol" pushes dark drum 'n' bass into IDM's twisted territory. And the industrial "Satan (Industry Standard)" even samples Butthole Surfers. A handful of sprawling mini-suites testify to the album's ambition, while the live tracks are proof of the duo's formidable stage presence.