iv 18 (Sie fürchten sich nämlich) by Mark Andre is a 44-minute work for double bass solo. It is a work from the iv-series by the composer Mark Andre. iv stands for introversion and the subtitle 'They are afraid' refers to a central passage from the Gospel of Mark and describes the unstable, the uncertain and the future. The world premiere took place on 11 September 2021 in Berlin at the Musikfest Berlin with Frank Reinecke (double bass).