The title mol-ecule, C(21)H(15)NO, has an indoline-2-one and two benzene substituent groups which are arranged in a propeller-like fashion around the central C atom. The dihedral angle between the two benzene rings is 73.32 (16)° and those between the benzene rings and the indoline-2-one group are 76.54 (14) and 67.69 (14)°. In the crystal, there is an inter-molecular N-H⋯O hydrogen-bonding inter-action, which links the mol-ecules into chains extending along c.