A phosphine-catalysed addition of gramine to an alkylideneaminonitrile gives the title compound, C25H24N4, in good yield. In the crystal, pairs of molecules are connected via N—H⋯N hydrogen bonds into inversion dimers. The molecules are characterized by a planar indole moiety [maximum deviation = 0.012 (1) Å], a chair conformation of the cyclohexane ring and an antiperiplanar conformation of the H atom on the cyclohexane and the adjacent cyano group.