Caspar Diethelm (1926-97) was one of the leading Swiss composers of the twentieth century. His free-tonal style - angular yet accessible - drew on the inheritance of several of his predecessors, above all Hindemith, Honegger (both of whom were his teachers), Martin and Schoeck, with Bartók adding rhythmic spice. These influences he combined with an awareness of modernism to form an individual and expressive musical language of his own. These chamber works for clarinet, covering over thirty years of creativity, are variously informed by lyrical tenderness, ironic humour, a dark sense of drama, edgy energy and light-hearted playfulness. Largely unknown until now, they constitute a major addition to the clarinettist's repertoire.