Darius Jones, Ryan Sawyer and Shahzad Ismaily at the Stone A simple truth about music is that it's good to be surprised. Ryan Sawyer, Darius Jones, and Shahzad Ismaily formed a trio late last year. They haven't made an album yet. Their set at the Stone on Tuesday night, as part of the Northern Spy record label's Spy Music Festival, was the group's third gig. Free improvising, a small room, standard instruments, stifling heat. But they pulled it off. They were surprising. How did they do it? Spy Music Festival From left, Darius Jones, Ryan Sawyer and Shahzad Ismaily performing a 40-minute set at the Stone on Tuesday night. It was the third show as a trio for these musicians, of different backgrounds, who came together as a group late last year. Improvising is an enormous idea. It means making something new on the spot, but what's newness? There's improvising on a song within an idiom, like Sonny Stitt playing "I Got Rhythm," or within a form or language, like raga or blues. There are various idioms of free improvising, with accepted instrumentation and strategies, like much of the music that descends from Cecil Taylor or late Coltrane; there's also improvising self-consciously outside of idiom, which has gone on for nearly half a century and has inevitably given rise to new kinds of idioms. But there are more options than that. There have to be. There are the endless forms of newness, for example, that can arise when people come from different backgrounds, which is the case here. Mr. Sawyer, a drummer, and Mr. Jones, an alto saxophonist, have internalized free jazz and the various languages around it; it's often a language of extremes, of great delicacy or full boil. They're used to it as an aesthetic and as a strategy. That's less true of Mr. Ismaily. He doesn't play much in any kind of jazz scene. He's a wild card among wild cards. You tend to find him in more song-oriented groups, with Bonnie Prince Billy, Faun Fables, Jolie Holland, Two Foot Yard, Marc Ribot's Ceramic Dog, but his role can seem fluid. He plays guitar, bass, drums and laptop, often all in the same set, arranging his tools around him and shifting from one to another, yet he's not particularly identified with any one of those instruments. He brings a sense of discovery. What he plays doesn't sound naïve; he's direct in finding the tone and phrasing he wants. But there is also sometimes the unsettling feeling that he is at least re-enacting the spirit of touching those instruments for the first time. Free improvisation can feel dogmatic, as if the musicians are at pains to embody an absolute principle, but this performance did not; the group seemed uninterested in that path. The musicians thought through everything as they went along. They kept their pieces short; they valued concision. They gravitated toward almost folklike themes and phrases, which all of them supplied. Mr. Jones played ballad tones and shrieked melodic repetitions without sentiment or aggression. Mr. Sawyer kept a steady free-rhythm simmer or played in time; Mr. Ismaily played notes and chords on one stringed instrument or another with great softness and then overdrive, with a clear amplified tone or ugly distortion or no amplification at all. Sometimes he made you feel silence, sometimes he blotted silence out. Whatever this music was, it was careful, and absolutely moment to moment. After 40 minutes, when the Stone's temperature had become unbearable, they stopped. A funny kind of mutual incomprehension hung in the air: the audience members didn't seem to know what they'd just heard, and neither did the musicians. The Spy Music Festival continues through July 15; spymusicfestival.com.