In the title compound, C20H15NOS, the dihedral angle between the phenyl rings is 74.25 (6)°. The six-membered 1,3-thia-zine ring has an envelope conformation with the C atom at the 2-position forming the flap. The crystal structure features weak C-H⋯O inter-actions, which lead to the formation of a tape motif along [110].