This mid-'60s session — featuring idiosyncratic composer/pianist Hill with a kickin' band that includes Joe Henderson and Freddie Hubbard — was inexplicably shelved by Blue Note and didn't fully see the light of day until 2006. As is usual for Hill, the music dances the line between post-bop structure and the avant-garde. His herky-jerky piano work is initially jarring but has an inner logic and quirky cohesion that keeps listeners on their toes. He and the band tackle six of his jittery, mostly hard-swinging tunes with an adroit combination of verve and sensitivity. Ultimately, Pax is challenging jazz that's eminently listenable.