Curtis Hasselbring's imagination has been captured by strange radio stations, and not NPR affiliates broadcasting trombone microtones on late-night avant-garde jazz programs. No, we're talking about something more curious than even that: short-wave stations that send out sequences of numbers thought to be coded instructions from intelligence agencies to their spies around the world. Number Stations, the Brooklyn trombonist's 2013 Cuneiform debut, is conceptualized around these stations that, as theorized by some (but denied by governments), set international espionage plans in motion. With liner notes citing "numeric information stored in the composed music" and "cryptic instructions for the musicians in the ensemble," one could easily surmise that Number Stations might be more intriguing for the participants than for the audience (see John Zorn's Cobra), but Hasselbring has succeeded in translating the mystery surrounding transmissions of cold arithmetic into a listening experience with all the atmospherics -- not to mention the attention-grabbing twists and turns -- of a classic spy thriller (and "hypothetically decoded" titles like "Avoid Sprinter" and "It's Not a Bunny" demonstrate that the composer of such previous tunes as "The Infinite Infiniteness of Infinity" hasn't lost his sense of humor). With Hasselbring's New Mellow Edwards quartet -- including reedman Chris Speed, bassist Trevor Dunn, and drummer Ches Smith -- supplemented by guitarist Mary Halvorson, drummer/percussionist Satoshi Takeishi, and vibraphonist/marimbist Matt Moran, the trombonist certainly has an extensive sonic palette to draw from. Which he does, from Takeishi's percussive tumblings echoing into the ether against the ensemble's insistent layered buildup on the opening "First Bus to Bismarck" (followed by Hasselbring's nicely spacious trombone solo over an increasingly agitated pulsing vamp) to the backbeat-driven closing number, "37° 56' 39" by 111° 32'," with Halvorson note-bending through a grungy counter-riff against Hasselbring and Speed's hooky front line. An irregular, Morse code-like bass vamp persists through most of "Tux Is Traitor," as Speed stretches out with his inimitable timbre after the band knots up in a fierce, angular attack, while "Make Anchor Babies" dives into breezy bossa-flavored sophisti-jazz, suggesting that even spies need an occasional break at the beach (as James Bond would confirm). Halvorson's prickly style is ideally suited to the music throughout Number Stations, and fans of Sonny Sharrock might particularly enjoy her fiery contributions to the concise "Green Dress, Maryland Welcome Center," where pounding rock meets rolling free jazz before concluding with an unexpectedly subtle feature for strummed guitar and Speed's sweet clarinet. Moran on vibes contributes greatly to the sometimes noir-ish atmosphere, while Hasselbring gives him an opportunity to stretch out over Dunn and Smith's alternatingly driving and elastic rhythms on the aforementioned ten-and-a-half-minute episodic "It's Not a Bunny." No decoding is necessary for full listener enjoyment of Number Stations, but note that if you merely download the album, you'll miss Steven "Human Lard Dog" Erdman's CD insert collages, which capture the project's attitude with a mixture of surrealism, Dadaism, and Manchurian Candidate-era paranoia. ~ Dave Lynch