It begins as do so many albums of so-called improvised music, slamming into gear at high-speed, both musicians blazing trails around each other at a pace far outstripping the ear's ability to follow, let alone the mind's to comprehend. Yet, that space is not the one saxophonist Trevor Watts and pianist Stephen Grew inhabit for long; the depths they plumb and the diversity with which they achieve maximum effect comprise just two of the ingredients making this trip through the improviser's orbit such a pleasant and exciting one.

Unpredictability is the session's watchword, a blessing for the poor writer far too often subjected to high-energy and low-contrast aimlessness foisted on listeners in the name of freedom. About halfway through "Shepherd's Return," there is a sudden decrease in activity as the back-and-forth conversational style of what might be called British improv is highlighted, slows and stops. Suddenly, the preparations in Grew's piano become more apparent, and equally suddenly, Watt's masterful responses to the four-note figures Grew repeats stand out in stark relief. Watts slides into a stunning display of syncopation, motivic development and phrase delivery that could be an encyclopedia entry for younger improvisers to study. The two begin to toy with scale, blending and contrasting harmony as leaves sprout from a tree and with equal malleability.

The rest of the album follows suit. Listen to the first sustained pitch Watts deftly inserts into the quartal and clusteral sonorities Grew's laying down as he builds his "Tunnels." Listen to the snapped B-flat with which Grew echoes Watt's second pitch, an absolute masterstroke of a response delivered as the sudden spark only intuition can ignite. Move to the gravitas of Watts' minor soliloquy opening "They're All Home," with its respectful nods toward silence, and feel the full impact of Grew's subtle and complete command of the piano's insides. The disc is a wondrous mixture of topic and texture, of technique and plain old soul. This is improvised music that speaks as much to the heart as to the head, and it demonstrates the fruitful relationship fostered by this intergenerational duo.