The call of the trombone leads this crew of improvisers in their quest for the infinite in the moments of inspiration that animate this music and make it worth the listen. Right from the first swirl of "Not Their Kind," we are drawn into the heat of the action, as the insistent piano chords struck by John Blum and the trippingly ecstatic drums and bass of Klaus Kugel and Matthew Heyner, respectively, set the scene for the dialogues and monologues of Swell and his horn-mate Sabir Mateen which culminate in the early moments of the most laconic piece of the session, "Sketch # 2."

A working band for a few years and now on their fourth installment of the current concept descriptively known as Slammin' the Infinite, this is a unit that plays tightly, whether they are in free-fall improvisation mode, or articulating the themes that serve as starting points for their inspired excursions. These include the bass-throttled theme of "Where are the Heartfelt," the peaceful and by turns disturbing introspections of "My Myth of Perfection," and the minor-key misterioso inflections that stop and start the improvised sections that make up "Sketch # 1."

As if Mateen's mastery of the alto and tenor saxophones, his primary axes, were not enough, he plays impressive flute (as in the sublime moments of abandoned in the piano/ flute tussle of "Sketch # 1") as well as Bb and alto clarinets. The structure of "Sketch #1" is indicative of the method here — a method which works — of group theme statements, interspersed by duos, first of flute and piano, then trombone and drums and finally a bass solo before a final restatement of the skeletal, yet distinctive and evocative theme.

The balanced juxtaposition of the pre-composed and the spontaneously invented make this a very satisfying listen, where interludes of theme and variations organically meld one into one another. And while a title like "The Only Way...Out," may suggest an aesthetic that prioritizes the dissonant and aleatory, that is not the whole story. This is a band that can improvise together, every step of the way.

The title of this outing, inspired by a Walt Whitman poem, is explained by the leader as "Only by constantly creating can there be any hope that some of that creating will yield something worthwhile," as "Farmers after all plant many seeds, not just one, in the hope that some of those seeds will yield a nourishing crop." The music here is certainly nourishing stuff to feed upon.