Kamal Humphrey de Inetagoyena, known to the world as Radioinactive, has a long history of hovering at the fringes of the hip-hop scene, gaining renown and cult admiration on the underground circuit but remaining too obtuse to ever be accepted by the mainstream. From his debut rapping in Pig Latin to his goat-voiced verse on the classic “Farmers Market of the Beast”, over the course of a solo album (Pyramidi) and two collaborations (2003’s The Weather with Busdriver and Daedelus and 2004’s Free Kamal with AntiMC) in addition to his work with the group Shape Shifters, Radioinactive has carved himself a niche as a fast-spitting, often abstract, intelligent rhymer, all leading up to Soundtrack to a Book, his second solo project and first release on Stranger Touch Records.

Musically, the beats have shifted from dirty, lo-fi hip-hop sounds to cleaner electronic production, but they fit Radioinactive’s flows remarkably well. “Refrigerator” is probably the best realization of his particular style here: the beat is laid-back and perfectly chilled, and Radi’’s rap chorus is deliberately-paced and unexceptional but at the same time oddly catchy. Then the beat shifts and Radioinactive catapults into hyper-speed-rapping, delivered in a buzzy, robotic monotone. Both the contrast between the two styles of rapping and the changing of the beat are executed masterfully, and they set the album’s level of potential high from early on.

Radioinactive plays with his flow interestingly throughout, although he leans somewhat heavily on plodding sing-rapping for his choruses—the lyrics don’t really hold up well under the closer examination that their slow repetition affords—but in between these choruses his vocals run the gamut from heavily-processed R&B crooning to stunningly fast torrents of syllables. On “Radiator”, Radio’s voice is filtered and altered until the words are completely unrecognizable, highlighting the rhythmic, complex-but-percussive nature of his rhyme patterns, while “Trouble” features possibly his fastest rapping to date. The actual content of the album strays deep into clean-cut nerd-rap territory “We are all the characters in a nineteenth-century novel / There were several vegetarian actors that are hanging at a McDonalds”), but unlike the subtler abstractions of MF DOOM or the crazed-intellectual rantings of Busdriver, Radio’s lines here all too often seem contrived simply to rhyme without any real deeper thought.

The biggest problem with the album is, sadly, length. At 10 tracks and less than half an hour of running time, Soundtrack to a Book has a hard time justifying its price tag. This is counting three less-than-a-minute interludes and one reprise, so all things being equal, there are only really six distinct tracks here, and the album ends up frustratingly toeing the line between LP and EP and leaning the wrong way for something billed as a full album.

In the end, Soundtrack to a Book ends up as a good introduction to the quirky MC that doesn’t reach the high level of his underground-classic collaboration with AntiMC, Free Kamal, but stands in its own right as a solid (if short) addition to his discography.