Mogwai's crash course in post-rock noise is a blistering jolt even to the most jaded of ears. On its fifth album, Mr. Beast, the band sounds singularly focused on re-discovering its dynamic roots, adding subtle flourishes along the way to avoid any self-referential mockery, and the result is decidedly retro for this typically forward-thinking Scottish quartet.

The piano-laced "Auto-Rock" is a driving dirge, building upon a simple, mournful phrase, twittering electronics, and a booming percussive thrust. The guitars weave in, layer upon layer, until the cacophony couldn't possibly be any louder. The cymbals surge in a clanging sheet of noise, but we quickly learn it's all a tease, as there's no pay-off or climax. Bastards.

The arpeggiated riffage of "Glasgow Mega-Snake" returns to vintage Mogwai, though, in heaving, heavy bursts of noise that ebb and flow in a lumbering, heavy-lidded sway. In the loud-is-more-but-louder-is-most spirit, the song climaxes repeatedly, dipping in and out of a soft/loud pattern, and ratcheting up the volume to ear-bleeding doses. Yessss.

Seemingly out of nowhere, Mogwai veers hard left into Western-tinged guitar balladry on "Acid Food", replete with vocoder, over-driven drum machines, and, believe it or not, pedal steel overdubs. It's gorgeously alluring in its simplicity and atmospheric effect, and shows that the band eschews stagnation as much as it aches to blow your hair back with sheer volume.

The post-rock genre has dug itself into a pretty confining hole over the last decade. Fewer and fewer bands even bother with the whole post-Slint schtick any more, which is a relief since barely any could actually pull it off with any panache. But Mogwai manages to balance its return to its roots with an ear for change. Mr. Beast isn't Mogwai's most challenging or daring record, but it might be its most beautiful or powerful.