Everyone’s gone concept album these days-even the hyperactive hardcore gabba/ragga kids. On How I Left You, Knifehandchop tells a breakup story through music. We start happily with “Goin’ Back to Scarborough,” which races melodies around and past a chunk of Dr. Dre. But by a few tracks in, even the sweetest piano lines start to become overwhelmed by noise, as on “Girlfriend.” The BPMs rarely let up, and as the hour grows later they signify more menace than excitement. Finally, Knifey finds solace where all the newly dumped seem to find it-dancing until dawn to “94 Hardcore.”