Andy Laster has been referred to as a "chamber jazz" musician and composer, a way of suggesting not only the small ensembles with which he tends to work, but also the hybrid of jazz and classical music he favors. Riptide is his first album to be billed by the artist himself as a chamber music effort, however, and in this case he means that it leans much more toward the classical side and that he is expressing himself solely as a composer; Laster's saxophone is nowhere to be found on the disc, and, in fact, he does not perform on the recordings at all. Instead, he employs a variety of musicians to play his compositions, some of whom, notably cellist Erik Friedlander, violist Stephanie Griffin, and conductor Mick Rossi, he has worked with extensively on other projects. The album is really something of a compilation of relatively short pieces that date back as far as 2001, which is the year of composition of the two parts of "Flagella" ("Mystérieuse" and "Très Agité"), a quartet work featuring pianist Eliran Avni, violinist Jennifer Choi, clarinetist Moran Katz, and cellist Hamilton Berry that is intended to be a musical representation of Piero della Francesca's 15th century painting The Flagellation. The most recent piece is also the most austere, the title track, a solo piano performance by Stephen Beck that is intended as program music, representing what it actually would feel like to be caught in a riptide. Although the album's compositions must be considered contemporary classical works, Laster does allow what he calls "structured improvisation" in "Genk" (a reflection of the composer's state of mind during a few days he was holed up in a hotel in this Belgian city, waiting for a jazz festival to start), the second movement of "String Trio No. 1," and the most ambitious piece, "Concrete Floor and Sailfish." Whether working from sheet music or navigating the uncharted improvised sections, Laster's musicians bravely address some challenging music here, addressing its sudden shifts of time and dynamics to get across the composer's feelings and states of mind. Listeners may not be quite as challenged as the musicians, but they also will have to engage with this complex music.