Like most musicians, trombonist Jacob Garchik found pandemic isolation nearly intolerable. Needing to do something, he assembled a lineup of close colleagues to record—in person, with enough separation—in an informal setting. The prompt given to soprano saxophonist Sam Newsome, pianist Jacob Sacks, bassist Thomas Morgan, and drummer Dan Weiss was to play straight-ahead jazz for fun, without pressure or expectations. Garchik then took the recordings from that day and used them as source material for the entirely new artistic statement that became Assembly. Easily one of the most striking musical responses to the quarantine, Assembly is also a fine example of remaining deeply rooted in the jazz tradition yet making that tradition responsive to musicians’ lives in the present. Nothing quite prepares the ear for the opener, “Collage,” a jumble of busy improvisation that somehow underscores a beautiful, out-of-tempo hymn, or “Fanfare,” a knotty, polyrhythmic descending figure that cuts away to trombone and piano playing Duke Ellington’s “In a Sentimental Mood.” These radical juxtapositions never come across as flippant. Rather, they reflect the players’ parallel commitments to “pure” jazz and following creativity wherever it leads.