In the title mol-ecule, C(24)H(17)N(3)O, the mean plane of the indolone ring forms dihedral angles of 112.0 (1) and 103.1 (1)° with the planes of the two indole rings. The dihedral angle between the mean planes of the two indole rings is 63.5 (1)°. In the crystal structure, mol-ecules are linked via inter-molecular N-H⋯O hydrogen bonds, forming a two-dimensional network parallel to the ab plane.