To paint is an apology for painting,” writes Marlene Dumas, in the introductory essay to her new show Mourning Marsyas. Discuss, I want to insist, as if her comment were an exam question. But before we can make any headway, she’s leading me from painting to painting, around Frith Street Gallery in London. There’s one of a rock that looks like a face. Other faces, stoic in grief and resilience, stare back. Elsewhere, there’s a looming timeless head called Nemesis that looks like it is out to get me. Figures and faces emerge from pours of paint that have provoked them into life. Some appear the work of an instant, others have been reworked. There are uneasy figures in rooms, awkward confrontations, paintings called War and Ceasefire. Some paintings allude obliquely to current conflicts, to terrible incidents, domestic dramas and personal distress. Others are closer to mythological nightmares. The devil’s in there too. We’ll come to him.