If any proof were needed that time flies, we have it in the fact that the National Galleries of Scotland’s NOW series of contemporary group shows has just revealed its fourth iteration, marking the halfway point in the three-year programme. So far, these shows – each one focusing on a single artist and radiating out in a range of directions – have proved surprising and revelatory, never pandering to the predictable. NOW 4 is no exception. Here, the central artist is Monster Chetwynd (formerly Marvin Gaye, Spartacus and Lali Chetwynd). She sets the tone for the show straight away, having designed wallpaper for the main corridor which splices together images from the NGS collection. Against this, and in good-natured argument with it, are prints from Goya’s Los Disparates series, because, for all its wacky contemporaneity, this NOW show is in more obvious dialogue with art history than any of its predecessors.