The asymmetric unit of the title compound, C19H16N2O3, comprises three independent mol­ecules (A, B and C). The inversion-related molecule of A is virtually superimposable upon the other two molecules. In each mol­ecule, there is a twist in the link between the approximately syn carbonyl and amine groups [the N—C—C—O torsion angles range from 19.73 (19) to −21.2 (2)°]. Each mol­ecule has a bent shape quanti­fied in terms of the dihedral angle between the indole and indole fused-ring systems [range = 45.69 (5)–47.91 (5)°]. In the crystal, the A and B mol­ecules form dimeric aggregates via ten-membered {⋯HNC2O}2 synthons, while the C mol­ecules self-associate similarly but about a centre of inversion.